Multi-beam active phased array architecture

ABSTRACT

In an exemplary embodiment, a phased array antenna comprises multiple subcircuits in communication with multiple radiating elements. The radio frequency signals are adjusted for both polarization control and beam steering. In a receive embodiment, multiple RF signals are received and combined into at least one receive beam output. In a transmit embodiment, at least one transmit beam input is divided and transmitted through multiple radiating elements. In an exemplary embodiment, the phased array antenna provides multi-beam formation over multiple operating frequency bands. The wideband nature of the active components allows for operation over multiple frequency bands simultaneously. Furthermore, the antenna polarization may be static or dynamically controlled at the subarray or radiating element level.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/412,901, entitled “MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE,”which was filed on Mar. 6, 2012, which is a continuation of U.S.application Ser. No. 12/759,059, now U.S. Pat. No. 8,160,530, which wasfiled on Apr. 13, 2010, which is a non-provisional of U.S. ProvisionalApplication No. 61/237,967, entitled “ACTIVE BUTLER AND BLASS MATRICES,”which was filed on Aug. 28, 2009, and is also a non-provisional of U.S.Provisional Application No. 61/259,375, entitled “ACTIVE HYBRIDS FORANTENNA SYSTEMS,” which was filed on Nov. 9, 2009, and is also anon-provisional of U.S. Provisional Application No. 61/234,513, entitled“ACTIVE FEED FORWARD AMPLIFIER,” which was filed on Aug. 17, 2009, andis also a non-provisional of U.S. Provisional Application No.61/222,354, entitled “ACTIVE PHASED ARRAY ARCHITECTURE,” which was filedon Jul. 1, 2009, and is also a non-provisional of U.S. ProvisionalApplication No. 61/168,913, entitled “ACTIVE COMPONENT PHASED ARRAYANTENNA,” which was filed on Apr. 13, 2009, and is also anon-provisional of U.S. Provisional Application No. 61/259,049, entitled“DYNAMIC REAL-TIME POLARIZATION FOR ANTENNAS,” which was filed on Nov.6, 2009, and is also a non-provisional of U.S. Provisional ApplicationNo. 61/234,521, entitled “MULTI-BAND MULTI-BEAM PHASED ARRAYARCHITECTURE,” which was filed on Aug. 17, 2009, and is also anon-provisional of U.S. Provisional Application No. 61/265,605, entitled“HALF-DUPLEX PHASED ARRAY ANTENNA SYSTEM,” which was filed on Dec. 1,2009, and is also a non-provisional of U.S. Provisional Application No.61/222,363, entitled “BIDIRECTIONAL ANTENNA POLARIZER,” which was filedon Jul. 1, 2009. All of the contents of the previously-identifiedapplications are hereby incorporated by reference for any purpose intheir entirety.

BACKGROUND

A phased array antenna uses multiple radiating elements to transmit,receive, or transmit and receive radio frequency (RF) signals. Phasedarray antennas are used in various capacities, including communicationson the move (COTM) antennas, satellite communication (SATCOM) airborneterminals, SATCOM mobile communications, and SATCOM earth terminals. Theapplication of mobile terminals typically requires the use of automatictracking antennas that are able to track the beam in azimuth, elevation,and polarization to follow the satellite position while the vehicle isin motion. Moreover, the antenna should be “low-profile,” small andlightweight, thereby fulfilling the stringent aerodynamic and massconstraints encountered in the typical mounting.

One well known type of phased array antenna is an electronicallysteerable phased array antenna. The electronically steerable phasedarray antenna has full electronic steering capability and is morecompact and lower profile than a comparable mechanical phased arrayantenna. The main drawback of fully electronic steering is that theantenna usually requires the integration of a lot of expensive analog RFelectronic components which may prohibitively raise the cost forcommercial applications. A typical electronically steerable phased arrayantenna comprises an assembly of phase shifters, power splitters, powercombiners, and quadrature hybrids. Additionally, a typicalelectronically steerable phased array requires at least a few of thesecomponents at every element in the phased array, which increases thecost and complexity of the architecture.

In a typical prior art embodiment and with reference to FIG. 1, a phasedarray antenna 100 comprises a radiating element 101 that communicatesdual linear signals to a hybrid coupler 102 (either 90° or 180°) andthen through low noise amplifiers 103, 104. Furthermore, the dualorthogonal signals are individually phase adjusted by phase shifters105, 106 before passing through a power combiner 107. In addition, thetypical components in a phased array antenna are distributed componentsthat are frequency sensitive and designed for specific frequency bands.

Phase shifters are used in a phased array antenna in order to steer thebeam of the signals by controlling the respective phases of the RFsignals communicated through the phase shifters. A typical digital phaseshifter uses switched delay lines, is physically large, and operatesover a narrow band of frequencies due to its distributed nature. Anothertypical digital phase shifter implements a switched high-pass low-passfilter architecture which has better operating bandwidth compared to aswitched delay line but is still physically large.

Also, the phase shifter is often made on gallium arsenide (GaAs). Thoughother materials may be used, GaAs is a higher quality material designedand controlled to provide good performance of electronic devices.However, in addition to being a higher quality material than the otherpossible materials, GaAs is also more expensive and more difficult tomanufacture. The typical phased array components take up a lot of areaon the GaAs, and result in higher costs. Furthermore, a standard phaseshifter has high RF loss, which is typically about n+1 dB of loss, wheren is the number of phase bits in the phase shifter. Another prior artembodiment uses RF MEMS switches and has lower loss but still consumessimilar space and is generally incompatible with monolithic solutions.

Quadrature hybrids or other differential phase generating hybrids areused in a variety of RF applications. In an exemplary embodiment,quadrature hybrids are used for generating circular polarizationsignals, power combining, or power splitting. In an exemplaryembodiment, the outputs of a quadrature hybrid have equal amplitude anda nominally 90° phase difference. In another typical embodiment, thequadrature hybrid is implemented as a distributed structure, such as aLange coupler, a branchline coupler, and/or the like. A 180° hybrid,such as a magic tee or a ring hybrid, results in a nominally 180° phaseshift. In general, quadrature hybrids and 180° hybrids are limited infrequency band and require significant physical space. Additionally,since the structures are distributed in nature, their physical sizeincreases with decreasing frequency. Moreover, the quadrature hybridsand 180° hybrids are typically made of GaAs and have associated RF powerloss on the order of 3-4 dB per hybrid when used as a power splitter,and an associated power loss of about 1 dB when used as a powercombiner.

In-phase power combiners and in-phase power splitters are also used in avariety of RF applications. In an exemplary embodiment, the outputs ofan in-phase hybrid have equal amplitude and a substantially zerodifferential phase difference. In another exemplary embodiment, theinputs of an in-phase hybrid configured as a power combiner encountersubstantially zero differential phase and amplitude shift. In a priorart embodiment, the in-phase hybrid is implemented as a distributedstructure such as a Wilkinson coupler. In general, an in-phase hybrid islimited in frequency band and requires significant physical space.Additionally, since the structure is distributed in nature, the physicalsize increases with decreasing frequency. The in-phase hybrid istypically made of GaAs. Moreover, the in-phase hybrid generally hasassociated RF power loss on the order of 3-4 dB per hybrid when used asa power splitter and an associated RF power loss of about 1 dB when usedas a power combiner.

In addition to the different components in a phased array antenna, anantenna signal can have different polarizations, namely linear,elliptical, or circular. Linear polarization consists of verticalpolarization and horizontal polarization, whereas circular polarizationconsists of left-hand circular polarization (LHCP) and right-handcircular polarization (RHCP). Elliptical polarization is similar tocircular polarization but occurs with different values for the verticaland horizontal component magnitudes or if the phase difference betweenthe vertical and horizontal components is a value other than 90°.

Conventional antennas utilize a fixed polarization that is hardwaredependant. The basis polarization is generally set during installationof the satellite terminal, at which point the manual configuration ofthe polarizer hardware is fixed. For example, a polarizer is generallyset for LHCP or RHCP and fastened into position. To change polarizationwould require unfastening the polarizer, rotating it 90° to the oppositecircular polarization, and then refastening the polarizer. Clearly thiscould not be done with much frequency and only a limited number (on theorder of 10 or maybe 20) of transceivers could be switched pertechnician in a given day.

Unlike a typical prior art single polarization antenna, some devices areconfigured to change polarizations without disassembling the antennaterminal. As an example and with reference to FIG. 2, a prior embodimentis the use of “baseball” switches to provide electronically commandableswitching between polarizations. As can be understood by the blockdiagram, the rotation of the “baseball” switches causes a change inpolarization by connecting one signal path to a waveguide whileterminating the other signal path. However, each “baseball” switch isphysically large and requires a separate rotational actuator withindependent control circuitry, which increases the cost of the devicesuch that this configuration is typically not used in consumer broadbandterminals.

Furthermore, another approach is to have a system with duplicatetransmit and receive hardware for each polarization. The polarizationselection is achieved by maintaining the path of the desired signal anddeselecting the undesired signal. However, doubling the hardware greatlyincreases the cost of the terminal. In yet another embodiment, a systemmay implement solid state diode or FET-based switches. The use of theseelectronic components may lead to high loss and limited power handlingin microwave and mm-wave applications. These alternatives are size,power, and cost prohibitive for most applications, including phasedarrays and low cost commercial applications.

Additionally, typical phased array antennas only form a single beam at atime and are often not capable of switching polarization. In order toform additional beams and/or have polarization switching ability fromthe same radiating aperture, additional phase shifting and powersplitting or combining components are required at every radiatingelement. These additional components are typically distributed innature, require significant physical space, are lossy, and only operateover relatively narrow frequency bands. For these reasons, polarizationagile, multiple beam phased array antennas that can operate overmultiple frequency bands are difficult to realize in practice.

Thus, a need exists for a phased array antenna architecture that is notfrequency limited or polarization specific, and that is reconfigurablefor different polarizations and able to transmit and/or receive overmultiple frequencies and form multiple beams. Furthermore, the antennaarchitecture should be able to be manufactured on a variety of materialsand with no associated RF loss. Also, a need exists for a phased arrayantenna that uses less space than a similar capability prior artarchitecture, is suitable for a monolithic implementation, and hascomponents with a physical size that is independent of operatingfrequency.

SUMMARY

An active phased array architecture may replace traditional distributedand GaAs implementations for the necessary functions required to operateelectronically steerable phased array antennas. The architecturecombines active versions of vector generators, power splitters, powercombiners, and/or RF hybrids in a novel fashion to realize a fully orsubstantially monolithic solution for a wide range of antennaapplications that can be realized with radiating elements havingdual-polarized feeds.

Overall, an active antenna polarizer is a digitally controlled activeimplementation for processing an RF signal. In accordance with anexemplary receive embodiment, the polarization and amplitude of the RFsignal communicated through a phased array radiating element isadjustable by operating two vector generators in parallel and feedingone or both output signals of the two vector generators to the radiatingelement in spatially orthogonal fashion. The phased array antenna isconfigured to electrically change between polarizations and/or supportbeam steering. For example, the phased array antenna may alternatebetween linear polarization, elliptical polarization, and circularpolarization. In accordance with an exemplary embodiment, in order tooperate in these different polarizations, vector generators control therelative phase of the antenna signal. In an exemplary embodiment, thebasic transmit embodiment and receive embodiment are used in anyfrequency band and with different polarizations.

In an exemplary embodiment, an active antenna polarizer is part of aphased array antenna that may be configured to transmit or receive an RFsignal. In one embodiment, the active antenna polarizer communicates asignal with linear polarization. In another embodiment, the activeantenna polarizer communicates a signal with dual polarization. In yetanother embodiment, a differential signal may be communicated usingeither linear polarization or dual polarization. Furthermore, theimplementation of dual-polarized feeds facilitates the operation ofphased arrays where the polarization can be statically or dynamicallycontrolled on a subarray or element basis.

In an exemplary embodiment, a phased array antenna comprises multiplesubcircuits in communication with multiple radiating elements. The radiofrequency signals are adjusted for both polarization control and beamsteering. In a receive embodiment, multiple RF signals are received andcombined into at least one receive beam output. In a transmitembodiment, at least one transmit beam input is divided and transmittedthrough multiple radiating elements.

In an exemplary embodiment, the phased array antenna provides multi-beamformation over multiple operating frequency bands. The phased arrayantenna replaces traditional distributed components and GaAs functionswith active components to operate an electronically steerable multiplebeam phased array antenna. The wideband nature of the active componentsallows for operation over multiple frequency bands simultaneously.Furthermore, the antenna polarization may be static or dynamicallycontrolled at the subarray or radiating element level.

Advantages of the exemplary phased array antenna include increasedsystem capacity and flexibility. Furthermore, an antenna that canoperate over multiple frequency bands optimizes system availability.This system may be implemented in mobile applications, or fixed positionapplications where multiple systems are desired. Also, a single antennacan communicate with multiple systems and/or users, allowing forincreased capacity and availability.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the drawing figures, wherein like reference numbersrefer to similar elements throughout the drawing figures, and:

FIG. 1 illustrates a prior art example of a phased array antenna elementand control electronics;

FIG. 2 illustrates a prior art example of an antenna with polarizationswitching;

FIG. 3 illustrates an exemplary embodiment of an active power splitter;

FIG. 4 illustrates an exemplary embodiment of an active power combiner;

FIG. 5 illustrates an exemplary embodiment of an active vectorgenerator;

FIG. 6 illustrates an exemplary embodiment of an active RF hybrid;

FIG. 7 illustrates an exemplary embodiment of an active antenna signalpolarizer;

FIG. 8 illustrates an exemplary embodiment of a phased array antennawith horizontal linear polarization for transmit mode;

FIG. 9 illustrates an exemplary embodiment of a phased array antennawith dual linear polarization for transmit mode;

FIG. 10 illustrates an exemplary embodiment of a phased array antennawith horizontal linear polarization for receive mode;

FIG. 11 illustrates an exemplary embodiment of a phased array antennawith dual linear polarization for receive mode;

FIG. 12 illustrates an exemplary embodiment of a phased array antennawith differentially fed horizontal linear polarization for transmitmode;

FIG. 13 illustrates an exemplary embodiment of a phased array antennawith differentially fed dual linear polarization for transmit mode;

FIG. 14 illustrates an exemplary embodiment of a phased array antennawith differentially fed horizontal linear polarization for receive mode;

FIG. 15 illustrates an exemplary embodiment of a phased array antennawith differentially fed dual linear polarization for receive mode;

FIG. 16 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 1-beam, 4-element transmitter;

FIG. 17 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 1-beam, 4-element receiver;

FIG. 18 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 2-beam, 4-element receiver;

FIG. 19 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 2-beam, 4-element transmitter;

FIG. 20 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 4-beam, 4-element receiver;

FIG. 21 illustrates an exemplary embodiment of a phased array integratedcircuit configured as a 4-beam, 4-element transmitter;

FIG. 22 illustrates another exemplary embodiment of a phased arrayintegrated circuit configured as a 2-beam, 4-element receiver;

FIG. 23 illustrates an exemplary embodiment of a multi-beamarchitecture;

FIG. 24 illustrates an exemplary embodiment of a dual-polarizationmulti-beam receive architecture;

FIG. 25 illustrates another exemplary embodiment of a dual-polarizationmulti-beam receive architecture;

FIG. 26 illustrates an exemplary embodiment of a dual-polarizationmulti-beam transmit architecture;

FIG. 27 illustrates another exemplary embodiment of a dual-polarizationmulti-beam transmit architecture;

FIG. 28 illustrates an exemplary embodiment of color distribution; and

FIGS. 29A-29C illustrate various satellite spot beam multicolor agilitymethods in accordance with exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION

While exemplary embodiments are described herein in sufficient detail toenable those skilled in the art to practice the invention, it should beunderstood that other embodiments may be realized and that logicalmaterial, electrical, and mechanical changes may be made withoutdeparting from the spirit and scope of the invention. Thus, thefollowing detailed description is presented for purposes of illustrationonly.

An electronically steerable phased array antenna may be used in variousscenarios. For example, the phased array antenna may be implemented inCOTM antennas, SATCOM airborne terminals, SATCOM mobile communications,and SATCOM earth terminals. In an exemplary embodiment, a phased arrayantenna comprises a layout of various active component building blocks,such as baluns, power splitters, power combiners, hybrids, and vectorgenerators. Although throughout the application reference may be made to“active power splitters, vector generators, and active power combiners”in various exemplary embodiments, only one or more of those devices maybe used in various embodiments, as opposed to all three devices.

A phased array antenna generally comprises multiple radiating elements,with each radiating element having a polarization component. In anexemplary embodiment, the radiating element has spatially orthogonallinear polarizations, spatially and electrically orthogonal circularpolarizations, or spatially orthogonal and electrically non-orthogonalelliptical polarizations. In an exemplary embodiment, a phased arrayantenna comprises various components. The various components may includea vector generator, an active power splitter, an active power combiner,or the like. Furthermore, in an exemplary embodiment, the phased arrayantenna comprises a patch antenna. Though a patch antenna is illustratedin the figures and described herein, other types of radiating elementsmay be implemented. Such radiating elements include a fragmentedradiator, a feed horn antenna, a slot antenna, and the like.

In an exemplary embodiment, each radiating element has two feed portsand results in an unbalanced feed system. In yet another exemplaryembodiment, each radiating element has three feed ports and results in apartially balanced feed system. In another exemplary embodiment, eachradiating element has four feed ports and results in a fully balancedfeed system.

In an exemplary embodiment, a phased array antenna with two feed portsis configured to generate and control different polarizations. Exemplarypolarization states include a single circular polarization state, asingle elliptical polarization state, a single linear polarizationstate, and two orthogonal linear polarization states.

The radiating elements may be in communication with an RF integratedcircuit (RFIC). In an exemplary embodiment, the RFIC is configured todivide, alter, and re-combine the basis polarizations to otherorthogonal polarization states. The RF signal corresponding to the netpolarization state in the RFIC may additionally be combined in abeam-forming network of the array.

Active Splitter:

FIG. 3 illustrates a schematic of an exemplary active power splitter. Inan exemplary embodiment, an active power splitter 300 comprises adifferential input subcircuit 310, a first differential outputsubcircuit 320, and a second differential output subcircuit 330. Thedifferential input subcircuit 310 has paired transistors 311, 312 with acommon emitter node and is constant current biased, as is typical in adifferential amplifier. An input signal is communicated to the base ofpaired transistors 311, 312 in the differential input subcircuit 310.Both the first and second differential output subcircuits 320, 330comprise a pair of transistors with a common base node and each commonbase is connected to ground.

The first differential output subcircuit 320 has a first transistor 321emitter connected to the collector of one of the input subcircuittransistors 312. The emitter of the second output subcircuit transistor322 is connected to the collector of the other input subcircuittransistor 311. In the exemplary embodiment, the first output is drawnfrom the collectors of transistors 321, 322 of the first differentialoutput subcircuit 320. Furthermore, the second differential outputsubcircuit 330 is similarly connected, except the transistor 331, 332emitters are inversely connected to the input subcircuit transistor 311,312 collectors with respect to transistors 321, 322.

By inverting the input subcircuit transistor collector connectionsbetween the first and second differential output subcircuits, the firstoutput and the second output are approximately 180° out of phase witheach other. In another exemplary embodiment, transistor 331, 332emitters are non-inversely connected to input subcircuit transistor 311,312 collectors, causing the first output and the second output to beapproximately in phase with each other. In general, the absolute phaseshift of the output signals through the power splitter is not asimportant as the relative phasing between the first and second outputsignals.

In an exemplary embodiment, active power splitter 300 converts an inputRF signal into two output signals. The output signal levels may be equalin amplitude, though this is not required. For a prior art passive powersplitter, each output signal would be about 3 dB lower in power than theinput signal. In contrast, an exemplary active splitter, such as activepower splitter 300, can provide gain and the relative power levelbetween the input signal and output signal is adjustable and can beselectively designed. In an exemplary embodiment, the output signal isconfigured to achieve a substantially neutral or positive power gainover the input signal. For example, the output signal may achieve a 3 dBsignal power gain over the input signal. In an exemplary embodiment, theoutput signal may achieve a power gain in the 0 dB to 5 dB range.Moreover, the output signal may be configured to achieve any suitablepower gain.

In accordance with an exemplary embodiment, active power splitter 300produces output signals with a differential phase between the twosignals that is zero or substantially zero. The absolute phase shift ofoutput signals through the active power splitter may not be as importantas the differential phasing between the output signals.

In another exemplary embodiment, active power splitter 300 additionallyprovides matched impedances at the input and output ports. The matchedimpedances may be 50 ohms, 75 ohms, or other suitable impedances.Furthermore, in an exemplary embodiment, active splitter 300 providesisolation between the output ports of the active power splitter. In oneexemplary embodiment, active power splitter 300 is manufactured as aradio frequency integrated circuit (RFIC) with a compact size that isindependent of the operating frequency due to a lack of distributedcomponents.

Active Combiner:

In an exemplary embodiment and with reference to FIG. 4, an active powercombiner 400 comprises a first differential input subcircuit 410, asecond differential input subcircuit 420, a single ended outputsubcircuit 430, and a differential output subcircuit 440. Eachdifferential input subcircuit 410, 420 includes two pairs oftransistors, with each transistor of each differential input subcircuit410, 420 having a common emitter node with constant current biasing, asis typical in a differential amplifier.

A first input signal is communicated to the bases of the transistors infirst differential input subcircuit 410. For example, a first line ofinput signal In1 is provided to one transistor of each transistor pairin first differential input subcircuit 410, and a second line of inputsignal In1 is provided to the other transistor of each transistor pair.Similarly, a second input signal is communicated to the bases of thetransistors in second differential input subcircuit 420. For example, afirst line of input signal In2 is provided to one transistor of eachtransistor pair in first differential input subcircuit 420, and a secondline of input signal In2 is provided to the other transistor of eachtransistor pair. Furthermore, in an exemplary embodiment, a differentialoutput signal is formed by a combination of signals from collectors oftransistors in first and second differential input subcircuits 410, 420.

In an exemplary embodiment, active power combiner 400 converts two inputRF signals into a single output signal. The output signal can either bea single ended output at single ended output subcircuit 430, or adifferential output at differential output subcircuit 440. In otherwords, active power combiner 400 performs a function that is the inverseof active power splitter 300. The input signal levels can be ofarbitrary amplitude and phase. Similar to an active power splitter,active power combiner 400 can provide gain and the relative power levelbetween the inputs and output is also adjustable and can be selectivelydesigned. In an exemplary embodiment, the output signal achieves asubstantially neutral or positive signal power gain over the inputsignal. For example, the output signal may achieve a 3 dB power gainover the sum of the input signals. In an exemplary embodiment, theoutput signal may achieve a power gain in the 0 dB to 5 dB range.Moreover, the output signal may achieve any suitable power gain.

In an exemplary embodiment, active power combiner 400 additionallyprovides matched impedances at the input and output ports. The matchedimpedances may be 50 ohms, 75 ohms, or other suitable impedances.Furthermore, in an exemplary embodiment, active power combiner 400provides isolation between the input ports of the power combiner. In oneexemplary embodiment, active power combiner 400 is manufactured as aRFIC with a compact size that is independent of the operating frequencydue to a lack of distributed components.

Vector Generator:

In an exemplary embodiment, a vector generator converts an RF inputsignal into an output signal (sometimes referred to as an output vector)that is shifted in phase and/or amplitude to a desired level. Thisreplaces the function of a typical phase shifter and adds the capabilityof amplitude control. In other words, a vector generator is a magnitudeand phase control circuit. In the exemplary embodiment, the vectorgenerator accomplishes this function by feeding the RF input signal intoa quadrature network resulting in two output signals that differ inphase by about 90°. The two output signals are fed into parallelquadrant select circuits, and then through parallel variable gainamplifiers (VGAs). In an exemplary embodiment, the quadrant selectcircuits receive commands and may be configured to either pass theoutput signals with no additional relative phase shift between them orinvert either or both of the output signals by an additional 180°. Inthis fashion, all four possible quadrants of the 360° continuum areavailable to both orthogonal signals. The resulting composite outputsignals from the current summer are modulated in at least one ofamplitude and phase.

In accordance with an exemplary embodiment and with reference to FIG. 5,a vector generator 500 comprises a passive I/Q generator 510, a firstVGA 520 and a second VGA 521, a first quadrant select 530 and a secondquadrant select 531 each configured for phase inversion switching, and acurrent summer 540. The first quadrant select 530 is in communicationwith I/Q generator 510 and first VGA 520. The second quadrant select 531is in communication with I/Q generator 510 and second VGA 521.Furthermore, in an exemplary embodiment, vector generator 500 comprisesa digital controller 550 that controls a first digital-to-analogconverter (DAC) 560 and a second DAC 561. The first and second DACs 560,561 control first and second VGAs 521, 520, respectively. Additionally,digital controller 550 controls first and second quadrant selects 530,531.

In an exemplary embodiment, vector generator 500 controls the phase andamplitude of an RF signal by splitting the RF signal into two separatevectors, the in-phase (I) vector and the quadrature-phase (Q) vector. Inone embodiment, the RF signal is communicated differentially. Thedifferential RF signal communication may be throughout vector generator500 or limited to various portions of vector generator 500. In anotherexemplary embodiment, the RF signals are communicatednon-differentially. The I vector and Q vector are processed in parallel,each passing through the phase inverting switching performed by firstand second quadrant selects 530, 531. The resultant outputs of the phaseinverting switches comprise four possible signals: a non-inverted I, aninverted I, a non-inverted Q, and an inverted Q. In this manner, allfour quadrants of a phasor diagram are available for further processingby VGAs 520, 521. In an exemplary embodiment, two of the four possiblesignals non-inverted I, inverted I, non-inverted Q, and inverted Q areprocessed respectively through VGAs 520, 521, until the two selectedsignals are combined in current summer 540 to form a composite RFsignal. The current summer 540 outputs the composite RF signal withphase and amplitude adjustments. In an exemplary embodiment, thecomposite RF signal is in differential signal form. In another exemplaryembodiment, the composite RF signals are in single-ended form.

In an exemplary embodiment, control for the quadrant shifting and VGAfunctions is provided by a pair of DACs. In an exemplary embodiment,reconfiguration of digital controller 550 allows the number of phasebits to be digitally controlled after vector generator 500 is fabricatedif adequate DAC resolution and automatic gain control (AGC) dynamicrange exists. In an exemplary embodiment with adequate DAC resolutionand AGC dynamic range, any desired vector phase and amplitude can beproduced with selectable fine quantization steps using digital control.In another exemplary embodiment, reconfiguration of DACs 560, 561 can bemade after vector generator 500 is fabricated in order to facilitateadjustment of the vector amplitudes.

Active RF Hybrid:

In an exemplary embodiment, and with reference to FIG. 6, an active RFhybrid 600 comprises a first active power splitter 610, a second activepower splitter 611, a first vector generator 620, a second vectorgenerator 621, a first active power combiner 630, a second active powercombiner 631, a first digital-to-analog converter (DAC) 640 and a secondDAC 641. In accordance with the exemplary embodiment, first active powersplitter 610 receives an input at Port 1 and communicates the input tofirst vector generator 620 and second active power combiner 631.Likewise, second active power splitter 611 receives an input at Port 2and communicates the input to second vector generator 621 and firstactive power combiner 630. Vector generators 620, 621 are controlled inpart by respective DACs 640, 641. In an exemplary embodiment, a 4-bitDAC is used but any number of bits many be used.

Furthermore, the output of first vector generator 620 is communicated tofirst active power combiner 630, and the output of second vectorgenerator 621 is communicated to second active power combiner 631. Inthe exemplary embodiment, first active power combiner 630 receives inputfrom first vector generator 620 and second active power splitter 611,and outputs a signal to Port 3. Similarly, second active power combiner631 receives input from second vector generator 621 and first activepower splitter 610, and outputs a signal to Port 4.

Active RF hybrid 600 may be used to replace various distributedcomponents, such as a branchline coupler, Lange coupler, directionalcoupler, or 180° hybrid. In accordance with an exemplary embodiment, anactive RF hybrid provides similar functionality in comparison to atraditional distributed hybrid. For example, active RF hybrid 600 may bedynamically configured to have variable phase differences between theoutput ports, which could be 90°, 180°, or some other phase difference.Another example is that active RF hybrid 600 provides port-to-portisolation and matched impedances at the input/output ports. Additionalinformation regarding active RF hybrids is disclosed in the U.S. patentapplication Ser. No. 12/759,043, entitled “ACTIVE HYBRIDS FOR ANTENNASYSTEMS,” filed the same day as this application, which is herebyincorporated by reference.

Furthermore, the active RF hybrid 600 has various advantages over atraditional passive distributed hybrid. In an exemplary embodiment, theactive RF hybrid 600 does not result in a loss of power, but instead hasa gain or is at least gain neutral. In another exemplary embodiment, theactive RF hybrid 600 does not rely on distributed elements and iscapable of operating over very wide bandwidths. In yet another exemplaryembodiment, the active RF hybrid 600 implements identical building blockcomponents as used in an exemplary active phased array architecture. Inone exemplary embodiment, the active RF hybrid 600 is manufactured as aMMIC with a compact size that is independent of the operating frequencydue to a lack of distributed components.

The components described above may be implemented in various phasedarray antenna embodiments. The various phased array antenna embodimentsinclude variations on transmit or receive embodiments, number of beams,different polarizations including linear, circular, and elliptical, andthe use of single ended signals or differentially fed signals.

In an exemplary embodiment, an electronically steerable phased arrayantenna comprises a radiating element array, an active vector generator,and a DAC. In one exemplary embodiment, the DAC is reconfigurable tooperate the phased array antenna in numerous configurations. Forexample, the phased array antenna can support multiple frequency bandsand be reprogrammed to change between different polarization types. Thereconfiguration can be made after the antenna architecture isfabricated.

In accordance with an exemplary embodiment, a phased array antennacomprises active components manufactured on silicon germanium (SiGe) ina monolithic solution. Other materials may be used, such as GaAs,silicon, or other suitable materials now known or hereinafter devised. Amonolithic SiGe embodiment using active components results in certainadvantages over the distributed/passive network in the prior art,including lower cost, smaller physical size, wider operating bandwidths,and the ability to provide power gain rather than a power loss.

Additionally, other advantages over the prior art embodiments arepossible, depending on the phased array architecture. Some of theadvantages include extensive system flexibility and very compact antennasystems because no distributed structures are required. In oneembodiment, the size of the control function components of the phasedarray architecture is compact and independent of operating frequency.Furthermore, some embodiments employ differential signaling to improvesignal isolation when the RF signal is in analog form.

Some of the main advantages include that RF signals undergo a neutral orslight positive gain when being communicated through the antenna system,rather than losses that occur in the passive prior art systems. Anotheradvantage is that the antenna system is not band limited. In otherwords, the antenna system is applicable to all frequency bands,including X, K, Ku, Ka, and Q bands. Furthermore, in an exemplaryembodiment, the antenna system is configured to operate, aftermanufacture or installation, at a first frequency range and subsequentlyoperate at a second frequency range not equal to the first frequencyrange. In another exemplary embodiment, the antenna system is configuredto operate at the first frequency range and the second frequency rangesimultaneously. In an exemplary embodiment, multi-band antennas are apractical option as a product.

Reconfigurability of the antenna system is also an advantage. Thisincludes the ability to reconfigure the number of phase bits over fullproduct life, being able to reconfigure the amplitude taper of thesystem over full product life, and being able to reconfigure the systempolarization over full product life.

Described below are various specific phased array antenna systemembodiments. The embodiments vary in terms of polarization, transmit orreceive modes, and whether differential signaling is implemented.

Active Antenna Polarizer:

Overall, an active antenna polarizer is a digitally controlled activeimplementation for processing an RF signal. In accordance with anexemplary embodiment, the polarization and amplitude of a phased arrayradiating element is adjustable by operating two vector generators inparallel and feeding both output signals of the two vector generators tothe radiating element in a spatially orthogonal fashion. The phasedarray antenna is configured to electrically change betweenpolarizations. For example, the phased array antenna may alternatebetween linear polarization and circular polarization. In a firstembodiment, the system achieves linear polarization by using a singlevector generator to drive the radiating element. In a second embodiment,the system achieves circular polarization by using two vector generatorsto drive the radiating element in a spatially orthogonal fashion withtwo vectors that are electrically 90° out of phase from each other. In athird embodiment, the system achieves elliptical polarization by usingtwo vector generators to drive the radiating element in a spatiallyorthogonal fashion with two vectors that are electrically out of phaseby a value other than 90° with each other.

In an exemplary embodiment, the active antenna polarizer comprisesdiscrete active components. In another exemplary embodiment, an activepolarizer comprises a monolithic solution of active components. In yetanother exemplary embodiment, the active antenna polarizer comprises acombination of discrete components and a monolithic solution.

In an exemplary embodiment and with reference to FIG. 7, a transmitactive antenna polarizer 700 comprises an active power splitter 710, twovector generators 720, 721, and two DACs 730, 731. An RF input signal isactively split and transmitted through two vector generators 720, 721 inparallel. The vector generators 720, 721 are controlled by DACs 730, 731respectively, and each vector generator produces a linear output signal.These two linear outputs can be used to energize/drive the spatiallyorthogonal feed ports of a radiating element (not shown).

The transmit active antenna polarizer 700 may be considered a basictransmit embodiment, which is configured to be implemented in a varietyof different phased array antenna architectures. In an exemplaryembodiment, the basic transmit embodiment is used in any frequency bandand with different polarizations. For example, and as described below,the basic transmit embodiment may be used as the basis for at least oneof beam steering and the phased array antenna transmitting in linearpolarization, circular polarization, or elliptical polarization. Inaccordance with an exemplary embodiment, in order to operate in thesedifferent polarizations, vector generators 720, 721 control the phase ofthe antenna signal. In another embodiment, vector generators 720, 721are configured for beam steering in conjunction with polarizationcontrol.

In an exemplary embodiment, reconfiguration of DACs 730, 731 allows thenumber of phase bits to be digitally controlled after transmit activeantenna polarizer 700 is fabricated if adequate DAC resolution and AGCdynamic range exists. In an exemplary embodiment with adequate DACresolution and AGC dynamic range, any desired vector phase and amplitudecan be produced with selectable fine quantization steps using digitalcontrol. In another exemplary embodiment, reconfiguration of DACs 730,731 can be made after transmit active antenna polarizer 700 isfabricated in order to facilitate adjustment of the signal amplitudes.

Reconfigurability of the antenna system is also an advantage. In anexemplary embodiment, the antenna system includes the ability toreconfigure the number of phase bits in a DAC over full product life. Inanother exemplary embodiment, the antenna system is able to reconfigurethe amplitude taper of the system over full product life. In yet anotherexemplary embodiment, the antenna system is able to reconfigure thesystem polarization over full product life. Moreover, in an exemplaryembodiment with adequate DAC resolution and AGC dynamic range, anydesired vector phase and amplitude can be produced with selectable finequantization steps using digital control.

In an exemplary embodiment, the vector generators are controlled bysoftware and digital hardware, and the antenna polarization is softwaredefinable. In other words, software may be implemented to control theantenna polarization by modifying the operating parameters of the vectorgenerators via the DACs or other digital control. The operatingparameters, for example, may include the relative phase between theoutputs of the vector generators. In an exemplary embodiment, softwarecontrols the phase change by programming the DACs to achieve the desiredphase relationship. Moreover, in an exemplary embodiment, thepolarization of the energy radiated from the antenna is controlled inreal-time. This results in a completely electronic technique wheresoftware allows continuous dynamic adjustment of the polarization ofdual polarization feed antennas.

A receive active antenna is similar to a transmit active antenna asalready described. In an exemplary embodiment, two RF input signals arecommunicated from a radiating element. The two RF input signals areprocessed in parallel through two vector generators before beingcombined by an active combiner. A receive active antenna polarizer maybe considered a basic receive embodiment which is configured to beimplemented in a variety of different phased array antennaarchitectures. In an exemplary embodiment, the basic receive embodimentis used in any frequency band and with different polarizations. Forexample, the basic receive embodiment may be used as the basis for atleast one of beam steering and the phased array antenna receiving inlinear polarization, circular polarization, or elliptical polarization.In accordance with an exemplary embodiment, in order to operate in thesedifferent polarizations, the vector generators control the phase of theantenna signal as described herein.

In accordance with an exemplary embodiment, an active antenna polarizeris configured to dynamically change the polarization of an antenna usingradiating elements with dual-polarized feeds. Furthermore, in anexemplary embodiment, an antenna is configured to statically ordynamically control the polarization of the antenna on a subarray orindividual element basis in order to optimize a performancecharacteristic associated with polarization. Examples of suchpolarization associated characteristics include polarization lossfactors and polarization efficiency. In an exemplary embodiment, the useof dual-polarized feeds facilitates the performance optimization. Forexample, in an exemplary embodiment, a maximum signal level may beobtained by varying the polarization around an expected value until theoptimal level is set. The difference between the expected value and theoptimal value may occur due to various factors. For example, objects maybe present in the signal path. As another example, manufacturingtolerances may result in the physical structure being in a less-optimalposition. In still another example, inclement weather can result in onepolarization performing better than another polarization. In otherwords, an exemplary antenna is configured to adjust the polarization inorder to compensate for manufacturing tolerances, weather, inferringobjects, and the like. In an exemplary embodiment, a polarization sweepis performed in order to receive different signals which can be used forsignal identification.

FIG. 8 shows an exemplary embodiment of a phased array antenna 800configured to transmit a signal with linear polarization. Phased arrayantenna 800 comprises an active power splitter 810, a first vectorgenerator 820, a second vector generator 821, a first DAC 830, and asecond DAC 831. Phased array antenna 800 is a basic transmit embodimentwith an output signal of first vector generator 820 energizing aradiating element 801 and with second vector generator 821 not incommunication with radiating element 801. In an alternative but similarembodiment, second vector generator 821 energizes radiating element 801with first vector generator 820 not in communication with radiatingelement 801. Additionally, radiating element 801 can have a “horizontal”orientation or a “vertical” orientation. In the exemplary embodiment,the basic transmit embodiment with two vector generators 820, 821 isimplemented in order to demonstrate that a standard architecture may beused in numerous antenna types. This enables cost benefits because thesame underlying component is used instead of different, more customizedcomponents.

In another exemplary embodiment, a phased array antenna, configured totransmit a signal with linear polarization, comprises only one vectorgenerator and a controlling DAC. As one skilled in the art understands,the embodiments described herein that manipulate only one vectorgenerator output can comprise only a single vector generator. In otherwords, in one embodiment, phased array antenna 800 comprises firstvector generator 820 but not second vector generator 821 or active powersplitter 810.

In contrast, a dual linear polarization antenna communicates two signalsto a radiating element. In an exemplary embodiment and with reference toFIG. 9, a phased array antenna 900 is configured to transmit a signalwith dual linear polarization. Phased array antenna 900 comprises anactive power splitter 910, a first vector generator 920, a second vectorgenerator 921, a first DAC 930, and a second DAC 931. Phased arrayantenna 900 is a basic transmit embodiment with the two vector generatoroutput signals energizing a radiating element 901, in both thehorizontal and vertical orientations. Furthermore, the output signals ofvector generators 920, 921 can have any relative phase between the twosignals. In a circular polarization embodiment, the output signal ofvector generator 920 has a +/−90° relative phase difference with theoutput signal of vector generator 921 when energizing radiating element901. In an exemplary embodiment with elliptical polarization, the outputsignal of vector generator 920 has a relative phase difference otherthan +/−90° with the output signal of vector generator 921 whenenergizing radiating element 901.

FIG. 10 shows an exemplary embodiment of a phased array antenna 1000configured to receive a signal with linear polarization. Phased arrayantenna 1000 comprises an active power combiner 1010, a first vectorgenerator 1020, a second vector generator 1021, a first DAC 1030 and asecond DAC 1031. Phased array antenna 1000 is a basic receive embodimentwith one of vector generators 1020, 1021 communicating a signal from aradiating element 1001 to active power combiner 1010 and the other ofvector generators 1020, 1021 not being in communication with radiatingelement 1001. Additionally, radiating element 1001 can have a horizontalor vertical orientation.

In another exemplary embodiment, a phased array antenna is configured toreceive a signal with linear polarization and comprises only one vectorgenerator and corresponding controlling DAC. As would be known to oneskilled in the art, various embodiments described herein that manipulateonly one vector generator output may comprise only one vector generator.In other words, in one embodiment, phased array antenna 1000 comprisesfirst vector generator 1020 but not second vector generator 1021 oractive combiner 1010.

In contrast, a dual linear polarization antenna communicates two signalsfrom a radiating element. In an exemplary embodiment and with referenceto FIG. 11, a phased array antenna 1100 is configured to receive asignal with dual linear polarization. Phased array antenna 1100comprises an active power combiner 1110, a first vector generator 1120,a second vector generator 1121, a first DAC 1130, and a second DAC 1131.Phased array antenna 1100 is a basic receive embodiment with vectorgenerators 1120, 1121 receiving individual polarized signals fromradiating element 1101 as input signals. The individual polarizedsignals may be a horizontal oriented signal and a vertical orientedsignal. Furthermore, the input signals of vector generators 1120, 1121can have any relative phase between the two signals. In a circularpolarization embodiment, the input signal of vector generator 1120 has a+/−90° relative phase difference with the input signal of vectorgenerator 1121 when received from radiating element 1101. In anexemplary embodiment with elliptical polarization, the input signal ofvector generator 1120 has a relative phase difference other than +/−90°with the input signal of vector generator 1121 when received fromradiating element 1101.

FIG. 12 shows an exemplary embodiment of a phased array antenna 1200configured to transmit a signal with differentially fed linearpolarization. Phased array antenna 1200 comprises an active powersplitter 1210, a first vector generator 1220, a second vector generator1221, a first DAC 1230 and a second DAC 1231. Phased array antenna 1200is a basic transmit embodiment with a differential output signal fromone of vector generators 1220, 1221 energizing a radiating element 1201.As is known to one in the art, a differential signal has two signals are180° out of phase from each other. In various embodiments, thedifferential signal may be fed into the “horizontal” portions ofradiating element 1201 or into the “vertical” portions of radiatingelement 1201.

In another exemplary embodiment, a phased array antenna configured totransmit a differential signal with linear polarization comprises onlyone vector generator and a controlling DAC. As one skilled in the artunderstands, the embodiments described herein that manipulate only onevector generator output can comprise only a single vector generator. Inother words, in one embodiment, phased array antenna 1200 comprisesfirst vector generator 1220 but not second vector generator 1221 oractive power splitter 1210.

In contrast, a dual linear polarization antenna communicates twodifferentially fed signals to a radiating element. In an exemplaryembodiment and with reference to FIG. 13, a phased array antenna 1300 isconfigured to transmit differential signals with dual linearpolarization. Phased array antenna 1300 comprises an active powersplitter 1310, a first vector generator 1320, a second vector generator1321, a first DAC 1330, and a second DAC 1331. Phased array antenna 1300is a basic transmit embodiment with a first differentially fed outputsignal of vector generator 1320 and a second differentially fed outputsignal of vector generator 1321 energizing a radiating element 1301. Inan exemplary embodiment, the first differentially fed output signal isfed into radiating element 1301 in a vertical orientation. Furthermore,in the exemplary embodiment, the second differentially fed output signalis fed into radiating element 1301 in a horizontal orientation.Moreover, the first differentially fed output signal of vector generator1320 and the second differentially fed output signal of vector generator1321 can have any relative phase between the two signals. In a circularpolarization embodiment, the first differentially fed output signal ofvector generators 1320 has a +/−90° relative phase difference with thesecond differentially fed output signal of vector generator 1321 whenenergizing radiating element 1301. In an exemplary embodiment withelliptical polarization, the first differentially fed output signal ofvector generator 1320 has a relative phase difference other than +/−90°with the second differentially fed output signal of vector generator1321 when energizing radiating element 1301.

FIG. 14 shows an exemplary embodiment of a phased array antenna 1400configured to receive a signal with differentially fed horizontal linearpolarization. Phased array antenna 1400 comprises an active powercombiner 1410, a first vector generator 1420, a second vector generator1421, a first DAC 1430 and a second DAC 1431. Phased array antenna 1400is a basic receive embodiment with one of vector generators 1420, 1421receiving a differential input signal from a radiating element 1401 andcommunicating an output signal to active power combiner 1410. In oneembodiment, and similar to phased array antenna 800, the other of vectorgenerators 1420, 1421 is not in communication with radiating element1401. Furthermore, the differential signal may be received from the“horizontal” portions of radiating element 1401 or from the “vertical”portions of radiating element 1401.

In another exemplary embodiment, a phased array antenna is configured toreceive a signal with differentially fed horizontal linear polarizationand comprises only one vector generator and corresponding controllingDAC. As would be known to one skilled in the art, various embodimentsdescribed herein that manipulate only one vector generator input maycomprise only one vector generator. In other words, in one embodiment,phased array antenna 1400 comprises first vector generator 1420 but notsecond vector generator 1421 or active combiner 1410.

In contrast, a dual linear polarization antenna communicates twodifferentially fed signals from a radiating element. In an exemplaryembodiment and with reference to FIG. 15, a phased array antenna 1500 isconfigured to receive differential signals with dual linearpolarization. Phased array antenna 1500 comprises an active powercombiner 1510, a first vector generator 1520, a second vector generator1521, a first DAC 1530, and a second DAC 1531. Phased array antenna 1500is a basic receive embodiment with vector generator 1520 receiving afirst differentially fed input signal and vector generator 1521receiving a second differentially fed input signal from a radiatingelement 1501. In an exemplary embodiment, the first differentially fedinput signal is received from radiating element 1501 in a verticalorientation. Furthermore, in the exemplary embodiment, the seconddifferentially fed input signal is received from radiating element 1501in a horizontal orientation. Moreover, the first and seconddifferentially fed input signals of vector generators 1520, 1521 canhave any relative phase between the two signals. In a circularpolarization embodiment, the first differentially fed input signal ofvector generator 1520 has a +/−90° relative phase difference with thesecond differentially fed input signal of vector generator 1521 whenreceived from radiating element 1501. In an exemplary embodiment withelliptical polarization, the first differentially fed output signal ofvector generator 1520 has a relative phase difference other than +/−90°with the second differentially fed output signal of vector generator1521 when energizing radiating element 1501.

The various phased array antenna embodiments described above may beimplemented into a multiple radiating element architecture. Furthermore,the multiple radiating elements are scalable in terms of both radiatingelements and beam forming. An embodiment with vector generators incommunication with individual radiating elements facilitates additionalbeams while using the same radiating aperture. Furthermore, theradiating element transmitter/receiver may comprise various numbers ofradiating elements. For example, the antenna architecture could comprisemultiple radiating elements in the range of 2-20.

In accordance with an exemplary embodiment, and with reference to FIG.16, a phased array integrated circuit (“IC”) 1600 is configured as a4-radiating element transmitter. The phased array IC 1600 comprises afirst subcircuit 1610 in communication with a first radiating element1611, a second subcircuit 1620 in communication with a second radiatingelement 1621, a third subcircuit 1630 in communication with a thirdradiating element 1631, and a fourth subcircuit 1640 in communicationwith a fourth radiating element 1641. Each subcircuit 1610, 1620, 1630,1640 receives an input signal and transmits the signal to the spatiallyorthogonal ports of the respective radiating element 1611, 1621, 1631,1641.

In accordance with an exemplary embodiment, an RF input signal isprovided to phased array IC 1600. In an exemplary embodiment, multiplesplitters are used to divide the RF input signal that is communicated toeach of four subcircuits 1610, 1620, 1630, 1640 as input signals. In amore specific exemplary embodiment, a balun may be implemented toconvert the RF input signal into a differential RF input signal.Differential signaling may improve signal isolation and interferencerejection if the RF signal is in analog form. An active splitter 1653 isconfigured to divide the differential RF input signal into two separatesignals that are communicated to an active splitter 1651 and an activesplitter 1652, respectively. At the next stage, active splitter 1651 isconfigured to divide the communicated signal and communicate the dividedsignals to first subcircuit 1610 and second subcircuit 1620. Similarly,active splitter 1652 is configured to divide the communicated signalsand communicate the divided signals to third subcircuit 1630 and fourthsubcircuit 1640.

The structure and function of each subcircuit 1610, 1620, 1630, 1640 issubstantially similar. Thus, only first subcircuit 1610 will bediscussed in detail. Moreover, subcircuit 1610 is substantially similarto transmit active antenna polarizer 700. In accordance with anexemplary embodiment, first subcircuit 1610 comprises a first vectorgenerator 1612 controlled by a first DAC (not shown), a second vectorgenerator 1613 controlled by a second DAC (not shown), and an activesplitter 1615. Though the signals communicated in phased array IC 1600may be described as differential, the signals may also be single-ended.Active splitter 1615 receives a differential signal from active splitter1651, and divides the differential signal once again. In an exemplaryembodiment, vector generators 1612, 1613 individually receive adifferential signal from active splitter 1615. Furthermore, vectorgenerators 1612, 1613 are configured to adjust the phase andpolarization of the signals to be transmitted so that individual beamsteering and polarization control may be achieved. Vector generators1612, 1613 afford two degrees of freedom to polarization track and beamsteer. For circular or elliptical polarization and single beam steering,one of the vector generators can provide the beam steering while theother vector generator can provide an offset phase to track thepolarization.

The polarized signals are then communicated from vector generators 1612,1613 to the spatially orthogonal ports of radiating element 1611 fortransmission. In an exemplary embodiment, a digital control 1601communicates polarization and beam steering commands to vectorgenerators 1612, 1613 via the respective DACs.

In addition to a 1-beam, 4-radiating element transmitter, a similarstructure may be configured as a 1-beam, 4-radiating element receiver.In an exemplary embodiment and with reference to FIG. 17, a phased arrayintegrated circuit 1700 is configured as a 1-beam, 4-radiating elementreceiver. The phased array IC 1700 comprises a first subcircuit 1710 incommunication with a first radiating element 1711, a second subcircuit1720 in communication with a second radiating element 1721, a thirdsubcircuit 1730 in communication with a third radiating element 1731,and a fourth subcircuit 1740 in communication with a fourth radiatingelement 1741. Each subcircuit 1710, 1720, 1730, 1740 receives a pair ofspatially orthogonal RF signals from the respectively coupled radiatingelement 1711, 1721, 1731, 1741 and generates a single output signal.

The structure and function of each subcircuit 1710, 1720, 1730, 1740 issubstantially similar. Thus, only first subcircuit 1710 will bediscussed in detail. In accordance with an exemplary embodiment, firstsubcircuit 1710 has a polarization tracking and single beam steeringportion comprising two vector generators 1712, 1713. The two vectorgenerators 1712, 1713 are configured to receive the RF input signal fromradiating element 1711, provide beam steering, track the polarization ofthe signals, and communicate the vector generator output signals to anactive power combiner 1715. Vector generators 1712, 1713 afford twodegrees of freedom to polarization track and beam steer. For circular orelliptical polarization and single beam steering, one of the vectorgenerators can provide the beam steering while the other vectorgenerator can provide an offset phase to track the polarization. Theactive power combiner 1715 combines the two vector generator outputsignals and generates a composite output signal.

In an exemplary embodiment, a digital control 1701 communicatespolarization and beam steering commands to vector generators 1712, 1713,for example, via corresponding DACs.

In accordance with an exemplary embodiment, a receive beam output isgenerated by combining the single output signal from each of foursubcircuits 1710, 1720, 1730, 1740. In an exemplary embodiment, multiplecombiners are used to combine the subcircuit output signals into areceive beam. In a more specific exemplary embodiment, an activecombiner 1751 is configured to combine the single outputs from first andsecond subcircuits 1710, 1720. Also in the exemplary embodiment, anactive combiner 1752 is configured to combine the single outputs fromthird and fourth subcircuits 1730, 1740. At the next stage, an activecombiner 1753 is configured to combine the combined outputs of activecombiners 1751, 1752 to form a receive beam output.

In addition to a 1-beam 4-radiating element antenna, a similar structuremay be configured as a 2-beam 4-radiating element antenna. In anexemplary embodiment and with reference to FIG. 18, a phased arrayintegrated circuit 1800 is configured as a 2-beam, 4-radiating elementreceiver. The phased array IC 1800 comprises a first subcircuit 1810 incommunication with a first radiating element 1811, a second subcircuit1820 in communication with a second radiating element 1821, a thirdsubcircuit 1830 in communication with a third radiating element 1831,and a fourth subcircuit 1840 in communication with a fourth radiatingelement 1841. Each subcircuit 1810, 1820, 1830, 1840 receives a pair ofspatially orthogonal RF signals from the respectively coupled radiatingelement 1811, 1821, 1831, 1841 and generates two output signals, one foreach beam to be formed.

The structure and function of each subcircuit 1810, 1820, 1830, 1840 issubstantially similar. Thus, only first subcircuit 1810 will bediscussed in detail. In accordance with an exemplary embodiment, firstsubcircuit 1810 has a polarization forming portion comprising two vectorgenerators 1812, 1813. The two vector generators 1812, 1813 areconfigured to receive the RF input signals from radiating element 1811,polarization track the signals, and transmit the vector generator outputsignals to an active power combiner 1815. The active power combiner 1815combines the two vector generator output signals and generates acomposite intermediate signal. The composite intermediate signal iscommunicated from active power combiner 1815 to an active power splitter1816. The active power splitter 1816 divides the intermediate signalinto two signals, one for each beam, with each of the two output signalspassing through a beam forming portion of subcircuit 1810. The beamforming portion comprises two vector generators 1818, 1819, whoseoutputs represent independently steered beam components to be combinedin the respective beam forming network. In an exemplary embodiment, adigital control 1801 communicates polarization and beam steeringcommands to vector generators 1812, 1813, 1818, 1819.

In accordance with an exemplary embodiment, a first receive beam outputis generated by combining one of the two output signals from each offour subcircuits 1810, 1820, 1830, 1840. A second receive beam output isgenerated by combining the second of the two output signals from each offour subcircuits 1810, 1820, 1830, 1840. In an exemplary embodiment,multiple combiners are used to combine the subcircuit output signalsinto a first receive beam output and a second receive beam output.

In a more specific exemplary embodiment, an active combiner 1851 isconfigured to combine the first of the two outputs from first and secondsubcircuits 1810, 1820. Furthermore, an active combiner 1861 isconfigured to combine the second of the two outputs from first andsecond subcircuits 1810, 1820. Also in the exemplary embodiment, anactive combiner 1852 is configured to combine the first of the twooutputs from third and fourth subcircuits 1830, 1840. An active combiner1862 is configured to combine the second of the two outputs from thirdand fourth subcircuits 1830, 1840.

At the next stage, an active combiner 1853 is configured to combine thecombined outputs of active combiners 1851 and 1852 to form a firstreceive beam output. Furthermore, an active combiner 1863 is configuredto combine the combined outputs of active combiners 1861 and 1862 toform a second receive beam output.

In addition to a 2-beam, 4-radiating element receiver, a similarstructure may be configured as a 2-beam, 4-radiating elementtransmitter. In an exemplary embodiment, and with reference to FIG. 19,a phased array integrated circuit 1900 is configured as a 2-beam,4-radiating element transmitter. The phased array IC 1900 comprises afirst subcircuit 1910 in communication with a first radiating element1911, a second subcircuit 1920 in communication with a second radiatingelement 1921, a third subcircuit 1930 in communication with a thirdradiating element 1931, and a fourth subcircuit 1940 in communicationwith a fourth radiating element 1941. Each subcircuit 1910, 1920, 1930,1940 receives two input signals and transmits signals to the spatiallyorthogonal ports of the respectively coupled radiating element 1911,1921, 1931, 1941.

In accordance with an exemplary embodiment, a first transmit beam and asecond transmit beam are provided to phased array IC 1900. In anexemplary embodiment, multiple splitters are used to divide the firstand second transmit beams that are communicated to each of foursubcircuits 1910, 1920, 1930, 1940 as input signals.

In a more specific exemplary embodiment, an active splitter 1953 isconfigured to divide the first transmit beam input into two separatesignals that are communicated to an active splitter 1951 and an activesplitter 1952, respectively. Similarly, an active splitter 1963 isconfigured to divide the second transmit beam input into two separatesignals that are communicated to an active splitter 1961 and an activesplitter 1962, respectively.

At the next stage, active splitters 1951, 1961 are configured to dividethe communicated signals and communicate the divided signals to firstsubcircuit 1910 and second subcircuit 1920. The active splitters 1952,1962 are configured to divide the communicated signals and communicatethe divided signals to third subcircuit 1930 and fourth subcircuit 1940.

The structure and function of each subcircuit 1910, 1920, 1930, 1940 issubstantially similar. Thus, only first subcircuit 1910 will bediscussed in detail. In accordance with an exemplary embodiment, firstsubcircuit 1910 has a beam forming portion comprising two vectorgenerators 1918, 1919. The two vector generators 1918, 1919 areconfigured to individually receive an input signal from active splitters1951, 1961, respectively and adjust the phase according to beam steeringcommands.

An active power combiner 1915 combines the two phase-adjusted signalsand generates a composite phase-adjusted intermediate signal. Thecomposite phase-adjusted intermediate signal is communicated from activepower combiner 1915 to an active power splitter 1916. The active powersplitter 1916 divides the intermediate signal into two splitter outputsignals, with each of the two splitter output signals passing through apolarization modifying portion of first subcircuit 1910. Thepolarization modifying portion comprises vector generators 1912, 1913,and is configured to polarize the output signals to the desiredpolarization. The polarized signals are then communicated to thespatially orthogonal ports of radiating element 1911 for transmission.In an exemplary embodiment, a digital control 1901 communicatespolarization and beam steering commands to vector generators 1912, 1913,1918, 1919.

In an exemplary embodiment and with reference to FIG. 20, a phased arrayintegrated circuit 2000 is configured as a 4-beam, 4-radiating elementreceiver. The phased array IC 2000 comprises a first subcircuit 2010 incommunication with a first radiating element 2011, a second subcircuit2020 in communication with a second radiating element 2021, a thirdsubcircuit 2030 in communication with a third radiating element 2031,and a fourth subcircuit 2040 in communication with a fourth radiatingelement 2041. Each subcircuit 2010, 2020, 2030, 2040 receives a pair ofspatially orthogonal RF signals from the respectively coupled radiatingelement 2011, 2021, 2031, 2041 and generates four output signals, onefor each beam to be formed.

The structure and function of each subcircuit 2010, 2020, 2030, 2040 issubstantially similar. Thus, only first subcircuit 2010 will bediscussed in detail. In accordance with an exemplary embodiment, firstsubcircuit 2010 has a polarization tracking portion comprising twovector generators 2012, 2013. The two vector generators 2012, 2013 areconfigured to receive the RF input signal from radiating element 2011,track the polarization of the signals, and transmit vector generatorsignal outputs to an active power combiner 2014. The active powercombiner 2014 combines the two vector generator signal outputs andgenerates a composite intermediate signal. The composite intermediatesignal is communicated from active power combiner 2014 to an activepower splitter 2015. The active power splitter 2015 divides theintermediate signal into four signals, with each of the four outputsignals passing through a beam forming portion of subcircuit 2010. Thebeam forming portion comprises four vector generators 2016, 2017, 20182019, whose outputs represent independently steered beam components tobe combined in the respective beam forming network. In an exemplaryembodiment, a digital control 2001 communicates polarization and beamsteering commands to vector generators 2012, 2013, 2016, 2017, 2018,2019.

In accordance with an exemplary embodiment, a first receive beam outputis generated by combining one of the four output signals from each offour subcircuits 2010, 2020, 2030, 2040. A second receive beam output isgenerated by combining a second of the four output signals from each offour subcircuits 2010, 2020, 2030, 2040. A third receive beam output isgenerated by combining a third of the four output signals from each offour subcircuits 2010, 2020, 2030, 2040. A fourth receive beam output isgenerated by combining a fourth of the four output signals from each offour subcircuits 2010, 2020, 2030, 2040. In an exemplary embodiment,multiple combiners are used to combine the subcircuit output signalsinto the four receive beam outputs.

In a more specific exemplary embodiment, an active combiner 2051 isconfigured to combine the first of the four outputs from first andsecond subcircuits 2010, 2020. Furthermore, an active combiner 2061 isconfigured to combine the second of the four outputs from first andsecond subcircuits 2010, 2020. Likewise, an active combiner 2071 isconfigured to combine the third of the four outputs from first andsecond subcircuits 2010, 2020. An active combiner 2081 is configured tocombine the fourth of the four outputs from first and second subcircuits2010, 2020.

Also in the exemplary embodiment, an active combiner 2052 is configuredto combine the first of the two outputs from third and fourthsubcircuits 2030, 2040. An active combiner 2062 is configured to combinethe second of the four outputs from third and fourth subcircuits 2030,2040. Furthermore, an active combiner 2072 is configured to combine thethird of the four outputs from third and fourth subcircuits 2030, 2040.An active combiner 2082 is configured to combine the fourth of the fouroutputs from third and fourth subcircuits 2030, 2040.

At the next stage, an active combiner 2053 is configured to combine thecombined outputs of active combiners 2051, 2052 to form a first receivebeam output. An active combiner 2063 is configured to combine thecombined outputs of active combiners 2061, 2062 to form a second receivebeam output. Furthermore, an active combiner 2073 is configured tocombine the combined outputs of active combiners 2071, 2072 to form athird receive beam output. An active combiner 2083 is configured tocombine the combined outputs of active combiners 2081, 2082 to form afourth receive beam output.

In an exemplary embodiment, and with reference to FIG. 21, a phasedarray integrated circuit 2100 is configured as a 4-beam, 4-radiatingelement transmitter. The phased array IC 2100 comprises a firstsubcircuit 2110 in communication with a first radiating element 2111, asecond subcircuit 2120 in communication with a second radiating element2121, a third subcircuit 2130 in communication with a third radiatingelement 2131, and a fourth subcircuit 2140 in communication with afourth radiating element 2141. Each subcircuit 2110, 2120, 2130, 2140receives four input signals and transmits RF signals to the spatiallyorthogonal ports of the respectively coupled radiating element 2111,2121, 2131, 2141.

In accordance with an exemplary embodiment, a first, second, third, andfourth transmit beam are provided to phased array IC 2100. In anexemplary embodiment, multiple splitters are used to divide the first,second, third, and fourth transmit beams that are communicated to eachof four subcircuits 2110, 2120, 2130, 2140 as input signals.

In a more specific exemplary embodiment, an active splitter 2153 isconfigured to divide the first transmit beam input into two separatesignals that are communicated to an active splitter 2151 and an activesplitter 2152, respectively. Similarly, an active splitter 2163 isconfigured to divide the second transmit beam input into two separatesignals that are communicated to an active splitter 2161 and an activesplitter 2162, respectively. In an exemplary embodiment, an activesplitter 2173 is configured to divide the third transmit beam input intotwo separate signals that are communicated to an active splitter 2171and an active splitter 2172, respectively. Furthermore, an activesplitter 2183 is configured to divide the fourth transmit beam inputinto two separate signals that are communicated to an active splitter2181 and an active splitter 2182, respectively.

At the next stage, active splitters 2151, 2161, 2171, 2181 areconfigured to divide the communicated signals and communicate thedivided signals to first subcircuit 2110 and second subcircuit 2120. Theactive splitters 2152, 2162, 2172, 2182 are configured to divide thecommunicated signals and communicate the divided signals to thirdsubcircuit 2130 and fourth subcircuit 2140.

The structure and function of each subcircuit 2110, 2120, 2130, 2140 issubstantially similar. Thus, only first subcircuit 2110 will bediscussed in detail. In accordance with an exemplary embodiment, firstsubcircuit 2110 has a beam forming portion comprising four vectorgenerators 2116, 2117, 2118, 2119. The four vector generators 2116,2117, 2118, 2119 are configured to individually receive an input signalfrom active splitters 2151, 2161, 2171, 2181, respectively and adjustthe phase according to beam steering commands.

An active power combiner 2114 combines the four phase-adjusted signalsand generates a composite phase-adjusted intermediate signal. Thecomposite phase-adjusted intermediate signal is communicated from activepower combiner 2114 to an active power splitter 2115. The active powersplitter 2115 divides the intermediate signal into two signals, witheach of the two output signals passing through a polarization modifyingportion of first subcircuit 2110. The polarization modifying portioncomprises vector generators 2112, 2113, and is configured to polarizethe output signals to the desired polarization. The polarized signalsare then communicated to the spatially orthogonal ports of radiatingelement 2111 for transmission. In an exemplary embodiment, a digitalcontrol 2101 communicates polarization and beam steering commands tovector generators 2112, 2113, 2116, 2117, 2118, 2119, for example, viaDACs.

In addition to the various embodiments described above, otherarchitectures are possible. For example, in an exemplary embodiment andwith reference to FIG. 22, a phased array integrated circuit 2200 isconfigured as a 2-beam, 4-radiating element receiver for circular orelliptical polarizations. As illustrated in a first subcircuit 2210 ofphased array IC 2200, the difference between phased array IC 1810 isthat only one vector generator 2212 is present in the polarizationforming portion. A single vector generator 2212 is sufficient forpolarization tracking of circular or elliptical polarizations. In anexemplary embodiment, vector generator 2212 tracks the polarizations byproviding the 90° offset (or non-90° phase offset if elliptical) to thephase of the signal appearing at the alternate spatially orthogonal portof radiating element 2211. The rest of phased array IC 2200 is similarto phased array IC 1810, and will not be described in detail thoughvarious components are similarly referenced. Similar variations arepossible in the embodiments illustrated in FIGS. 19-21, with circular orelliptical polarization embodiments using only a single vector generatorfor polarization tracking.

Multi-Beam Operation:

In addition to the multiple radiating elements embodiments describedabove, various beam forming networks may be designed using multipleradiating elements and forming multiple beams. In accordance with anexemplary embodiment and with reference to FIG. 23, a multi-beamarchitecture 2300 comprises multiple radiating elements (RE₁, RE₂, . . .RE_(N)) with each radiating element being in communication with anactive polarization control (PC₁, PC₂, . . . PC_(N)). The multi-beamarchitecture 2300 further comprises at least one beam forming network(BFN₁, BFN₂, . . . BFN_(m)) and at least one phase shifter connected tothe active polarization control (PC₁, PC₂, . . . PC_(N)) per beamforming network (BFN₁, BFN₂, . . . BFN_(m)). In an exemplary embodiment,each radiating element is in communication with M phase shifters, andeach phase shifter is in communication with one of M beam formingnetworks so that each beam forming network receives a signal from eachof the N radiating elements.

In an exemplary embodiment, the phase shifters may be active vectorgenerators or any other component suitable to phase shift the signals.Furthermore, the beam forming networks and summing junctions can bepassive or active. Moreover, a multi-beam architecture may similarly beimplemented for transmission of RF signals.

With further reference to FIG. 23, the active polarization controlfunctions (PC₁, PC₂, . . . PC_(N)) can be any of the embodimentspreviously listed herein. Connected to each of the active polarizationcontrol functions is a power splitter (for receive applications) orpower combiner (for transmit applications). The power splitter or powercombiner can be implemented as a passive or active structure asdescribed previously herein. In communication with the powersplitter/combiner is a set of vector generators where each vectorgenerator provides a phase shift in support of a particular beam. In anexemplary embodiment, there are M vector generators at each radiatingelement to support M independently steerable beams. In an exemplaryembodiment, the set of vector generators is in communication with apower combiner (for receive applications) or power splitter (fortransmit applications) to complete the beam formation process. The powersplitter or power combiner can be implemented as a passive or activestructure as described previously herein.

In different various embodiments, a multi-beam multi-band architecturewith a beam forming network in communication with a single radiatingelement is configured for forming and detecting circular polarizedsignals.

Receive Architecture:

In accordance with an exemplary embodiment and with reference to FIG.24, dual-polarization multi-beam receive architecture 2400 comprisesactive power splitters, vector generators, and active power combiners incommunication with a radiating element 2401 to form multiple beams. Inan exemplary embodiment, receive architecture 2400 forms at least oneright-hand circular polarized (RHCP) beam and forms at least oneleft-hand circular polarized (LHCP) beam. More specifically, in anexemplary embodiment, receive architecture 2400 forms N RHCP beams andforms M LHCP beams.

Each beam, whether right-hand polarized or left-hand polarized, isformed using a similar component configuration. In an exemplaryembodiment, a signal is received at radiating element 2401, having ahorizontal polarization and a vertical polarization. The verticalpolarized signal is communicated to a first active power splitter 2410and the horizontal polarized signal is communicated to a second activepower splitter 2411. Moreover, first active power splitter 2410 mayrefer to multiple active power splitters, and second active powersplitter 2411 may refer to the same number of multiple active powersplitters. In an exemplary embodiment, active power splitters 2410, 2411individually divide the signal into two or more signals, such that thevertical signal polarization and horizontal signal polarization aredivided into a certain number of signals.

In an exemplary embodiment, each beam is formed using a first vectorgenerator 2420, a second vector generator 2421, and an active powercombiner 2430. The first vector generator 2420 receives a verticalpolarized signal from first active power splitter 2410. First vectorgenerator 2420 is configured to adjust at least one of the phase andamplitude of the vertical polarized signal for beam steering.Furthermore, second vector generator 2421 receives a horizontalpolarized signal from second active power splitter 2411. Second vectorgenerator 2421 is configured to adjust at least one of the phase andamplitude of the horizontal polarized signal for polarization tracking.In other embodiments, the vertical polarized signal is adjusted forpolarization tracking and the horizontal polarized signal is adjustedfor beam steering. In accordance with an exemplary embodiment, activepower combiner 2430 receives two output signals, one signal from firstvector generator 2420 and another signal from second vector generator2421. Active power combiner 2430 combines the two signals into a beam.The beam may be RHCP or LHCP, depending on the parameters of vectorgenerators 2420, 2421. In an exemplary embodiment, receive architecture2400 is configured to provide complete polarization flexibility on abeam by beam basis. However, receive architecture 2400 uses 2*(M+N)vector generators to accomplish this complete flexibility.

In a circular polarization embodiment, fewer components are used incomparison to a complete polarization embodiment because circularpolarization only needs +/−90° polarization tracking. Therefore, in anexemplary embodiment and with reference to FIG. 25, a dual-polarizationmulti-beam receive architecture 2500 with circular polarizationcomprises active power splitters and vector generators in communicationwith a radiating element 2501 to form multiple beams.

In an exemplary embodiment, receive architecture 2500 forms at least oneRHCP beam and forms at least one LHCP beam. As with the completepolarization embodiment, receive architecture 2500 may form up to N RHCPbeams and M LHCP beams. Each beam, whether right-hand polarized orleft-hand polarized, is formed using a similar component configuration.In an exemplary embodiment, a signal is received at radiating element2501, having a horizontal polarization component and a verticalpolarization component. The vertical polarized signal is communicated toa first active power splitter 2510 and the horizontal polarized signalis communicated to a second active power splitter 2511. Moreover, firstactive power splitter 2510 may refer to multiple active power splitters,and second active power splitter 2511 may refer to the same number ofmultiple active power splitters. In an exemplary embodiment, activepower splitters 2510, 2511 individually divide the signal into two ormore signals, such that the vertical signal polarization and horizontalsignal polarization are divided into a certain number of signals.

In an exemplary embodiment, each beam is formed using a vector generator2520 and a quadrature allpass filter (QAF) 2540. In an exemplaryembodiment, QAF 2540 receives a vertical polarized signal from firstactive power splitter 2510 and a horizontal polarized signal from secondactive power splitter 2511. QAF 2540 combines the vertical andhorizontal polarized signals while injecting a nominally 90° relativephase shift between the two signals. The combined output signal iscommunicated from QAF 2540 to vector generator 2520. Vector generator2520 is configured to provide beam steering by adjusting at least one ofthe phase and amplitude of the combined signal.

The beam may be RHCP or LHCP, depending on the signal input connectionswith QAF 2540. For example, to generate a RHCP beam, a verticalpolarized signal is connected to an I vector input of QAF 2540 and ahorizontal polarized signal is connected to a Q vector input of QAF2540. In contrast, to generate a LHCP beam, a vertical polarized signalis connected to the Q vector input of QAF 2540 and a horizontalpolarized signal is connected to the I vector input of QAF 2540. In anexemplary embodiment, receive architecture 2500 provides circularpolarization on each beam using (M+N) vector generators.

In another exemplary embodiment, a simpler component configuration of adual-polarization multi-beam receive architecture with circularpolarization is possible. Similar to receive architecture 2500, in anexemplary embodiment, a receive architecture comprises a first activepower splitter, a second active power splitter and a modified vectorgenerator in communication with a radiating element. However, incontrast to receive architecture 2500, no quadrature allpass filters areused. For each beam, and still using receive architecture 2500 as areference, QAF 2540 is eliminated in conjunction with eliminating theQAF at the input of vector generator 2520, resulting in a modifiedvector generator.

The elimination of the two QAF components is a result of redundancy. Inreceive architecture 2500, QAF 2540 receives two input vectors, referredto as a Q vector and an I vector for convenience. With reference tosimilar vector generator 500, vector generator 2520 also comprises a QAFthat is separate and reversed from QAF 2540. In vector generator 2520,the QAF receives a single signal and generates a Q vector and an Ivector. In an exemplary embodiment, the cascade of two reversed QAFsperforms a redundant function and may be eliminated. In the exemplaryembodiment, the vertical and horizontal polarized signals from theradiating element are connected to the phase inversion switches of amodified vector generator. The elimination of QAFs is possible if theQAFs are originally reversed of each other. In other words, reversedback-to-back QAFs injecting opposite phase shifts counteract each otherand become expendable.

Eliminating the two QAFs achieves system advantages, such as eliminatingthe ohmic loss associated with each QAF, which may be about 3 dB.Another advantage is that the QAF is a bandwidth limiting element of thevector generator, resulting in the modified vector generator beingcapable of an expanded bandwidth.

Transmit Architecture:

In accordance with an exemplary embodiment and with reference to FIG.26, dual-polarization multi-beam transmit architecture 2600 comprisesactive power splitters, vector generators, and active power combiners incommunication with a radiating element 2601 to form a dual polarizedtransmit signal from multiple input beams. In an exemplary embodiment,transmit architecture 2600 generates a dual polarized transmit signalfrom at least one RHCP beam and from at least one LHCP beam. Morespecifically, in an exemplary embodiment, transmit architecture 2600inputs include N RHCP beams and M LHCP beams.

Each beam, whether right-hand polarized or left-hand polarized, is addedto the dual polarized output signal using a similar componentconfiguration. In an exemplary embodiment, an active power splitter 2610receives a beam having either right-hand or left-hand circularpolarization and divides the beam into two divided signals. A firstvector generator 2620 receives one of the two divided signals at theinput. A second vector generator 2621 receives the other of the twodivided signals at the input. First vector generator 2620 is configuredto adjust at least one of the phase and amplitude of the divided signalfor beam steering. Second vector generator 2621 is configured to adjustat least one of the phase and amplitude of the divided signal forpolarization tracking. In other embodiments, first vector generator 2620performs polarization tracking and second vector generator 2621 performsbeam steering.

Furthermore, in an exemplary embodiment first vector generator 2620generates a vertically polarized signal that is combined with othervertically polarized signals in a first active power combiner 2630. Thecombined output signal of first active power combiner 2630 istransmitted to radiating element 2601 as a vertical polarization signal.Moreover, in the exemplary embodiment second vector generator 2621generates a horizontally polarized signal that is combined with otherhorizontally polarized signals in a second active power combiner 2631.The combined output signal of second active power combiner 2631 istransmitted to radiating element 2601 as a horizontal polarizationsignal. Active power combiner 2630 may refer to multiple active powercombiners, and second active power combiner 2631 may refer to the samenumber of multiple active power combiners. In an exemplary embodiment,transmit architecture 2600 is configured to provide completepolarization flexibility on a beam by beam basis. However, transmitarchitecture 2600 uses 2*(M+N) vector generators to accomplish thiscomplete flexibility.

In a circular polarization embodiment, fewer components are used incomparison to a complete polarization embodiment because circularpolarization only needs +/−90° polarization tracking. Therefore, in anexemplary embodiment and with reference to FIG. 27, a dual-polarizationmulti-beam transmit architecture 2700 with circular polarizationcomprises vector generators and active power combiners in communicationwith a radiating element 2701 to form a dual polarized transmit signalfrom multiple input beams. In an exemplary embodiment, transmitarchitecture 2700 generates a dual polarized transmit signal from atleast one RHCP beam and from at least one LHCP beam. As with thecomplete polarization embodiment, transmit architecture 2700 inputsinclude N RHCP beams and M LHCP beams.

Each beam, whether right-hand polarized or left-hand polarized, is addedto the dual polarized output signal using a similar componentconfiguration. In an exemplary embodiment, a vector generator 2720receives an input beam. Vector generator 2720 is configured to adjust atleast one of the phase and amplitude of the input beam. The outputsignal of vector generator 2720 is communicated to a QAF 2740. In anexemplary embodiment, QAF 2740 divides output signal into a verticalsignal and a horizontal signal while injecting a nominally 90° relativephase shift between the two signals to generate vertical and horizontalpolarizations.

Furthermore, in an exemplary embodiment QAF 2740 generates a verticallypolarized signal that is combined with other vertically polarizedsignals in a first active power combiner 2730. The combined outputsignal of first active power combiner 2730 is transmitted to radiatingelement 2701 as a vertical polarization signal. Moreover, in theexemplary embodiment QAF 2740 also generates a horizontally polarizedsignal that is combined with other horizontally polarized signals in asecond active power combiner 2731. The combined output signal of secondactive power combiner 2731 is transmitted to radiating element 2701 as ahorizontal polarization signal. Active power combiner 2730 may refer tomultiple active power combiners, and second active power combiner 2731may refer to the same number of multiple active power combiners.

In an exemplary embodiment, transmit architecture 2700 adjusts for theinput beam having either RHCP or LHCP by alternating which output signalof QAF 2740 is communicated to each active power combiner. For example,and as illustrated in FIG. 27, for a RHCP beam, a vertical polarizedsignal is connected to an I vector output of QAF 2740. In contrast, fora LHCP, a vertical polarized signal is connected to a Q vector output ofQAF 2740. In an exemplary embodiment, transmit architecture 2700 forms adual polarized output signal from circular polarized input beams using(M+N) vector generators.

Although FIGS. 24-27 illustrate a one dimensional phased array, a twodimensional phased array is also contemplated and would be understood byone skilled in the art.

In an exemplary embodiment, software reconfiguration of the vectorgenerators occurs in real-time as the system is operating, which enablesa phased array antenna to have the capabilities previously described.Additionally, in the exemplary embodiment, there are no hardware changesthat require physical and/or manual operations for polarization changingor system alterations. In other words, in an exemplary embodiment, thephased array antenna is fully electronically adjusted, which results ingreater degrees of freedom compared to typical systems. Furthermore, thedynamic control of signal polarization of a phased array antenna hasnumerous applications.

In one application embodiment, dynamic control of signal polarization isimplemented for secure communications by utilizing polarization hopping.Communication security can be enhanced by changing the polarization of acommunications signal at a rate known to other authorized users. Anunauthorized user will not know the correct polarization for any giveninstant and if using a constant polarization, the unauthorized userwould only have the correct polarization for brief instances in time. Asimilar application to polarization hopping for secure communications isto use polarization hopping for signal scanning. In other words, thepolarization of the antenna can be continuously adjusted to monitor forsignal detection.

In an exemplary embodiment, dynamic control of signal polarizationfacilitates radar target identification using a single antenna. Radartarget identification systems use information from multiplepolarizations to provide increased target identification information.Additionally, a reflected signal's polarization and signal strength canbe changed by the object off which it reflects. Thus, in an exemplaryembodiment, a single antenna is configured to receive multiplepolarizations and produce better identification due to acquiring moreinformation about the target.

4 Color System:

In the field of consumer satellite RF communication, a satellite willtypically transmit and/or receive data (e.g., movies and othertelevision programming, internet data, and/or the like) to consumers whohave personal satellite dishes at their home. More recently, thesatellites may transmit/receive data from more mobile platforms (suchas, transceivers attached to airplanes, trains, and/or automobiles). Itis anticipated that increased use of handheld or portable satellitetransceivers will be the norm in the future. Although sometimesdescribed in this document in connection with home satellitetransceivers, the prior art limitations now discussed may be applicableto any personal consumer terrestrial transceivers (or transmitters orreceivers) that communicate with a satellite.

A propagating radio frequency (RF) signal can have differentpolarizations, namely linear, elliptical, or circular. Linearpolarization consists of vertical polarization and horizontalpolarization, whereas circular polarization consists of left-handcircular polarization (LHCP) and right-hand circular polarization(RHCP). An antenna is typically configured to pass one polarization,such as LHCP, and reject the other polarization, such as RHCP.

Also, conventional very small aperture terminal (VSAT) antennas utilizea fixed polarization that is hardware dependent. The basis polarizationis generally set during installation of the satellite terminal, at whichpoint the manual configuration of the polarizer hardware is fixed. Forexample, a polarizer is generally set for LHCP or RHCP and fastened intoposition. To change polarization in a conventional VSAT antenna mightrequire unfastening the polarizer, rotating it 90° to the oppositecircular polarization, and then refastening the polarizer. Clearly thiscould not be done with much frequency and only a limited number (on theorder of 5 or maybe 10) of transceivers could be switched per technicianin a given day.

Unlike a typical single polarization antenna, some devices areconfigured to change polarizations without disassembling the antennaterminal. As an example, a prior embodiment is the use of “baseball”switches to provide electronically commandable switching betweenpolarizations. The rotation of the “baseball” switches causes a changein polarization by connecting one signal path and terminating the othersignal path. However, each “baseball” switch requires a separaterotational actuator with independent control circuitry, which increasesthe cost of device such that this configuration is not used (if at all)in consumer broadband or VSAT terminals, but is instead used for largeground stations with a limited number of terminals.

Furthermore, another approach is to have a system with duplicatehardware for each polarization. The polarization selection is achievedby completing or enabling the path of the desired signal and deselectingthe undesired signal. This approach is often used in receive-onlyterminals, for example satellite television receivers having low-costhardware. However, with two way terminals that both transmit and receivesuch as VSAT or broadband terminals, doubling the hardware greatlyincreases the cost of the terminal.

Conventional satellites may communicate with the terrestrial basedtransceivers via radio frequency signals at a particular frequency bandand a particular polarization. Each combination of a frequency band andpolarization is known as a “color.” The satellite will transmit to alocal geographic area with signals in a “beam” and the geographic areathat can access signals on that beam may be represented by “spots” on amap. Each beam/spot will have an associated “color.” Thus, beams ofdifferent colors will not have the same frequency, the samepolarization, or both.

In practice, there is some overlap between adjacent spots, such that atany particular point there may be two, three, or more beams that are“visible” to any one terrestrial transceiver. Adjacent spots willtypically have different “colors” to reduce noise/interference fromadjacent beams.

In the prior art, broadband consumer satellite transceivers aretypically set to one color and left at that setting for the life of thetransceiver. Should the color of the signal transmitted from thesatellite be changed, all of the terrestrial transceivers that werecommunicating with that satellite on that color would be immediatelystranded or cut off. Typically, a technician would have to visit theconsumer's home and manually change out (or possibly physicallydisassemble and re-assemble) the transceiver or polarizer to make theconsumer's terrestrial transceiver once again be able to communicatewith the satellite on the new “color” signal. The practical effect ofthis is that in the prior art, no changes are made to the signal colortransmitted from the satellite.

For similar reasons, a second practical limitation is that terrestrialtransceivers are typically not changed from one color to another (i.e.,if they are changed, it is a manual process). Thus, there is a need fora new low cost method and device to remotely change the frequency and/orpolarization of an antenna system. There is also a need for a method anddevice that may be changed nearly instantaneously and often.

In spot beam communication satellite systems, both frequency andpolarization diversity are utilized to reduce interference from adjacentspot beams. In an exemplary embodiment, both frequencies andpolarizations are re-used in other beams that are geographicallyseparated to maximize communications traffic capacity. The spot beampatterns are generally identified on a map using different colors toidentify the combination of frequency and polarity used in that spotbeam. The frequency and polarity re-use pattern is then defined by howmany different combinations (or “colors”) are used.

In accordance with various exemplary embodiments and with reference toFIG. 28, an antenna system is configured for frequency and polarizationswitching. In one specific exemplary embodiment, the frequency andpolarization switching comprises switching between two frequency rangesand between two different polarizations. This may be known as four colorswitching. In other exemplary embodiments, the frequency andpolarization switching comprises switching between three frequencyranges and between two different polarizations, for a total of sixseparate colors. Furthermore, in various exemplary embodiments, thefrequency and polarization switching may comprise switching between twopolarizations with any suitable number of frequency ranges. In anotherexemplary embodiment, the frequency and polarization switching maycomprise switching between more than two polarizations with any suitablenumber of frequency ranges.

In accordance with various exemplary embodiments, the ability to performfrequency and polarization switching has many benefits in terrestrialmicrowave communications terminals. For example, doing so may facilitateincreased bandwidth, load shifting, roaming, increased datarate/download speeds, improved overall efficiency of a group of users onthe system, or improved individual data communication rates. Terrestrialmicrowave communications terminals, in one exemplary embodiment,comprise point to point terminals. In another exemplary embodiment,terrestrial microwave communications terminals comprise ground terminalsfor use in communication with any satellite, such as a satelliteconfigured to switch frequency range and/or polarity of a RF signalbroadcasted. These terrestrial microwave communications terminals arespot beam based systems.

In accordance with various exemplary embodiments, a satellite configuredto communicate one or more RF signal beams each associated with a spotand/or color has many benefits in microwave communications systems. Forexample, similar to what was stated above for exemplary terminals inaccordance with various embodiments, doing so may facilitate increasedbandwidth, load shifting, roaming, increased data rate/download speeds,improved overall efficiency of a group of users on the system, orimproved individual data communication rates. In accordance with anotherexemplary embodiment, the satellite is configured to remotely switchfrequency range and/or polarity of a RF signal broadcasted by thesatellite. This has many benefits in microwave communications systems.In another exemplary embodiment, satellites are in communications withany suitable terrestrial microwave communications terminal, such as aterminal having the ability to perform frequency and/or polarizationswitching.

Prior art spot beam based systems use frequency and polarizationdiversity to reduce or eliminate interference from adjacent spot beams.This allows frequency reuse in non-adjacent beams resulting in increasedsatellite capacity and throughput. Unfortunately, in the prior art, inorder to have such diversity, installers of such systems must be able toset the correct polarity at installation or carry different polarityversions of the terminal. For example, at an installation site, aninstaller might carry a first terminal configured for left handpolarization and a second terminal configured for right handpolarization and use the first terminal in one geographic area and thesecond terminal in another geographic area. Alternatively, the installermight be able to disassemble and reassemble a terminal to switch it fromone polarization to another polarization. This might be done, forexample, by removing the polarizer, rotating it 90°, and reinstallingthe polarizer in this new orientation. These prior art solutions arecumbersome in that it is not desirable to have to carry a variety ofcomponents at the installation site. Also, the manualdisassembly/reassembly steps introduce the possibility of human errorand/or defects.

These prior art solutions, moreover, for all practical purposes,permanently set the frequency range and polarization for a particularterminal. This is so because any change to the frequency range andpolarization will involve the time and expense of a service call. Aninstaller would have to visit the physical location and change thepolarization either by using the disassembly/re-assembly technique or byjust switching out the entire terminal. In the consumer broadbandsatellite terminal market, the cost of the service call can exceed thecost of the equipment and in general manually changing polarity in suchterminals is economically unfeasible.

In accordance with various exemplary embodiments, a low cost system andmethod for electronically or electro-mechanically switching frequencyranges and/or polarity is provided. In an exemplary embodiment, thefrequency range and/or polarization of a terminal can be changed withouta human touching the terminal. Stated another way, the frequency rangeand/or polarization of a terminal can be changed without a service call.In an exemplary embodiment, the system is configured to remotely causethe frequency range and/or polarity of the terminal to change.

In one exemplary embodiment, the system and method facilitate installinga single type of terminal that is capable of being electronically set toa desired frequency range from among two or more frequency ranges. Someexemplary frequency ranges include receiving 10.7 GHz to 12.75 GHz,transmitting 13.75 GHz to 14.5 GHz, receiving 18.3 GHz to 20.2 GHz, andtransmitting 28.1 GHz to 30.0 GHz. Furthermore, other desired frequencyranges of a point-to-point system fall within 15 GHz to 38 GHz. Inanother exemplary embodiment, the system and method facilitateinstalling a single type of terminal that is capable of beingelectronically set to a desired polarity from among two or morepolarities. The polarities may comprise, for example, left handcircular, right hand circular, vertical linear, horizontal linear, orany other orthogonal polarization. Moreover, in various exemplaryembodiments, a single type of terminal may be installed that is capableof electronically selecting both the frequency range and the polarity ofthe terminal from among choices of frequency range and polarity,respectively.

In an exemplary embodiment, transmit and receive signals are paired sothat a common switching mechanism switches both signals simultaneously.For example, one “color” may be a receive signal in the frequency rangeof 19.7 GHz to 20.2 GHz using RHCP, and a transmit signal in thefrequency range of 29.5 GHz to 30.0 GHz using LHCP. Another “color” mayuse the same frequency ranges but transmit using RHCP and receive usingLHCP. Accordingly, in an exemplary embodiment, transmit and receivesignals are operated at opposite polarizations. However, in someexemplary embodiments, transmit and receive signals are operated on thesame polarization which increases the signal isolation requirements forself-interference free operation.

Thus, a single terminal type may be installed that can be configured ina first manner for a first geographical area and in a second manner fora second geographical area that is different from the first area, wherethe first geographical area uses a first color and the secondgeographical area uses a second color different from the first color.

In accordance with an exemplary embodiment, a terminal, such as aterrestrial microwave communications terminal, may be configured tofacilitate load balancing. In accordance with another exemplaryembodiment, a satellite may be configured to facilitate load balancing.Load balancing involves moving some of the load on a particularsatellite, or point-to-point system, from one polarity/frequency range“color” or “beam” to another. In an exemplary embodiment, the loadbalancing is enabled by the ability to remotely switch frequency rangeand/or polarity of either the terminal or the satellite.

Thus, in exemplary embodiments, a method of load balancing comprises thesteps of remotely switching frequency range and/or polarity of one ormore terrestrial microwave communications terminals. For example, systemoperators or load monitoring computers may determine that dynamicchanges in system bandwidth resources has created a situation where itwould be advantageous to move certain users to adjacent beams that maybe less congested. In one example, those users may be moved back at alater time as the loading changes again. In an exemplary embodiment,this signal switching (and therefore this satellite capacity “loadbalancing”) can be performed periodically. In other exemplaryembodiments, load balancing can be performed on many terminals (e.g.,hundreds or thousands of terminals) simultaneously or substantiallysimultaneously. In other exemplary embodiments, load balancing can beperformed on many terminals without the need for thousands of userterminals to be manually reconfigured.

In one exemplary embodiment, dynamic control of signal polarization isimplemented for secure communications by utilizing polarization hopping.Communication security can be enhanced by changing the polarization of acommunications signal at a rate known to other authorized users. Anunauthorized user will not know the correct polarization for any giveninstant and if using a constant polarization, the unauthorized userwould only have the correct polarization for brief instances in time. Asimilar application to polarization hopping for secure communications isto use polarization hopping for signal scanning. In other words, thepolarization of the antenna can be continuously adjusted to monitor forsignal detection.

In an exemplary embodiment, the load balancing is performed asfrequently as necessary based on system loading. For example, loadbalancing could be done on a seasonal basis. For example, loads maychange significantly when schools, colleges, and the like start and endtheir sessions. As another example, vacation seasons may give rise tosignificant load variations. For example, a particular geographic areamay have a very high load of data traffic. This may be due to a higherthan average population density in that area, a higher than averagenumber of transceivers in that area, or a higher than average usage ofdata transmission in that area. In another example, load balancing isperformed on an hourly basis. Furthermore, load balancing could beperformed at any suitable time. In one example, if maximum usage isbetween 6-7 PM then some of the users in the heaviest loaded beam areascould be switched to adjacent beams in a different time zone. In anotherexample, if a geographic area comprises both office and home terminals,and the office terminals experience heaviest loads at different timesthan the home terminals, the load balancing may be performed betweenhome and office terminals. In yet another embodiment, a particular areamay have increased localized signal transmission traffic, such asrelated to high traffic within businesses, scientific researchactivities, graphic/video intensive entertainment data transmissions, asporting event or a convention. Stated another way, in an exemplaryembodiment, load balancing may be performed by switching the color ofany subgroup(s) of a group of transceivers.

In an exemplary embodiment, the consumer broadband terrestrial terminalis configured to determine, based on preprogrammed instructions, whatcolors are available and switch to another color of operation. Forexample, the terrestrial terminal may have visibility to two or morebeams (each of a different color). The terrestrial terminal maydetermine which of the two or more beams is better to connect to. Thisdetermination may be made based on any suitable factor. In one exemplaryembodiment, the determination of which color to use is based on the datarate, the download speed, and/or the capacity on the beam associatedwith that color. In other exemplary embodiments, the determination ismade randomly, or in any other suitable way.

This technique is useful in a geographically stationary embodimentbecause loads change over both short and long periods of time for avariety of reasons and such self adjusting of color selectionfacilitates load balancing. This technique is also useful in mobilesatellite communication as a form of “roaming.” For example, in oneexemplary embodiment, the broadband terrestrial terminal is configuredto switch to another color of operation based on signal strength. Thisis, in contrast to traditional cell phone type roaming, where thatroaming determination is based on signal strength. In contrast, here,the color distribution is based on capacity in the channel. Thus, in anexemplary embodiment, the determination of which color to use may bemade to optimize communication speed as the terminal moves from one spotto another. Alternatively, in an exemplary embodiment, a color signalbroadcast by the satellite may change or the spot beam may be moved andstill, the broadband terrestrial terminal may be configured toautomatically adjust to communicate on a different color (based, forexample, on channel capacity).

In accordance with another exemplary embodiment, a satellite isconfigured to communicate one or more RF signal beams each associatedwith a spot and/or color. In accordance with another exemplaryembodiment, the satellite is configured to remotely switch frequencyrange and/or polarity of a RF signal broadcasted by the satellite. Inanother exemplary embodiment, a satellite may be configured to broadcastadditional colors. For example, an area and/or a satellite might onlyhave 4 colors at a first time, but two additional colors, (making 6total colors) might be dynamically added at a second time. In thisevent, it may be desirable to change the color of a particular spot toone of the new colors. With reference to FIG. 29A, spot 4 changes from“red” to then new color “yellow.” In one exemplary embodiment, theability to add colors may be a function of the system's ability tooperate, both transmit and/or receive over a wide bandwidth within onedevice and to tune the frequency of that device over that widebandwidth.

In accordance with an exemplary embodiment, and with renewed referenceto FIG. 28, a satellite may have a downlink, an uplink, and a coveragearea. The coverage area may be comprised of smaller regions eachcorresponding to a spot beam to illuminate the respective region. Spotbeams may be adjacent to one another and have overlapping regions. Asatellite communications system has many parameters to work: (1) numberof orthogonal time or frequency slots (defined as color patternshereafter); (2) beam spacing (characterized by the beam roll-off at thecross-over point); (3) frequency re-use patterns (the re-use patternscan be regular in structures, where a uniformly distributed capacity isrequired); and (4) numbers of beams (a satellite with more beams willprovide more system flexibility and better bandwidth efficiency).Polarization may be used as a quantity to define a re-use pattern inaddition to time or frequency slots. In one exemplary embodiment, thespot beams may comprise a first spot beam and a second spot beam. Thefirst spot beam may illuminate a first region within a geographic area,in order to send information to a first plurality of subscriberterminals. The second spot beam may illuminate a second region withinthe geographic area and adjacent to the first region, in order to sendinformation to a second plurality of subscriber terminals. The first andsecond regions may overlap.

The first spot beam may have a first characteristic polarization. Thesecond spot beam may have a second characteristic polarization that isorthogonal to the first polarization. The polarization orthogonalityserves to provide an isolation quantity between adjacent beams.Polarization may be combined with frequency slots to achieve a higherdegree of isolation between adjacent beams and their respective coverageareas. The subscriber terminals in the first beam may have apolarization that matches the first characteristic polarization. Thesubscriber terminals in the second beam may have a polarization thatmatches the second characteristic polarization.

The subscriber terminals in the overlap region of the adjacent beams maybe optionally assigned to the first beam or to the second beam. Thisoptional assignment is a flexibility within the satellite system and maybe altered through reassignment following the start of service for anysubscriber terminals within the overlapping region. The ability toremotely change the polarization of a subscriber terminal in anoverlapping region illuminated by adjacent spot beams is an importantimprovement in the operation and optimization of the use of thesatellite resources for changing subscriber distributions andquantities. For example it may be an efficient use of satelliteresources and improvement to the individual subscriber service toreassign a user or a group of users from a first beam to a second beamor from a second beam to a first beam. Satellite systems usingpolarization as a quantity to provide isolation between adjacent beamsmay thus be configured to change the polarization remotely by sending asignal containing a command to switch or change the polarization from afirst polarization state to a second orthogonal polarization state. Theintentional changing of the polarization may facilitate reassignment toan adjacent beam in a spot beam satellite system using polarization forincreasing a beam isolation quantity.

The down link may comprise multiple “colors” based on combinations ofselected frequency and/or polarizations. Although other frequencies andfrequency ranges may be used, and other polarizations as well, anexample is provided of one multicolor embodiment. For example, and withrenewed reference to FIG. 28, in the downlink, colors U1, U3, and U5 areLeft-Hand Circular Polarized (“LHCP”) and colors U2, U4, and U6 areRight-Hand Circular Polarized (“RHCP”). In the frequency domain, colorsU3 and U4 are from 18.3-18.8 GHz; U5 and U6 are from 18.8-19.3 GHz; andU1 and U2 are from 19.7-20.2 GHz. It will be noted that in thisexemplary embodiment, each color represents a 500 MHz frequency range.Other frequency ranges may be used in other exemplary embodiments. Thus,selecting one of LHCP or RHCP and designating a frequency band fromamong the options available will specify a color. Similarly, the uplinkcomprises frequency/polarization combinations that can be eachdesignated as a color. Often, the LHCP and RHCP are reversed asillustrated, providing increased signal isolation, but this is notnecessary. In the uplink, colors U1, U3, and U5 are RHCP and colors U2,U4, and U6 are LHCP. In the frequency domain, colors U3 and U4 are from28.1-28.6 GHz; U5 and U6 are from 28.6-29.1 GHz; and U1 and U2 are from29.5-30.0 GHz. It will be noted that in this exemplary embodiment, eachcolor similarly represents a 500 MHz frequency range.

In an exemplary embodiment, the satellite may broadcast one or more RFsignal beam (spot beam) associated with a spot and a color. Thissatellite is further configured to change the color of the spot from afirst color to a second, different, color. Thus, with renewed referenceto FIG. 29A, spot 1 is changed from “red” to “blue.”

When the color of one spot is changed, it may be desirable to change thecolors of adjacent spots as well. Again with reference to FIG. 29A, themap shows a group of spot colors at a first point in time, where thisgroup at this time is designated 9110, and a copy of the map shows agroup of spot colors at a second point in time, designated 9120. Some orall of the colors may change between the first point in time and thesecond point in time. For example spot 1 changes from red to blue andspot 2 changes from blue to red. Spot 3, however, stays the same. Inthis manner, in an exemplary embodiment, adjacent spots are notidentical colors.

Some of the spot beams are of one color and others are of a differentcolor. For signal separation, the spot beams of similar color aretypically not located adjacent to each other. In an exemplaryembodiment, and with reference again to FIG. 28, the distributionpattern illustrated provides one exemplary layout pattern for four colorspot beam frequency re-use. It should be recognized that with thispattern, color U1 will not be next to another color U1, etc. It shouldbe noted, however, that typically the spot beams will over lap and thatthe spot beams may be better represented with circular areas ofcoverage. Furthermore, it should be appreciated that the strength of thesignal may decrease with distance from the center of the circle, so thatthe circle is only an approximation of the coverage of the particularspot beam. The circular areas of coverage may be overlaid on a map todetermine what spot beam(s) are available in a particular area.

In accordance with an exemplary embodiment, the satellite is configuredto shift one or more spots from a first geographic location to a secondgeographic location. This may be described as shifting the center of thespot from a first location to a second location. This might also bedescribed as changing the effective size (e.g., diameter) of the spot.In accordance with an exemplary embodiment, the satellite is configuredto shift the center of the spot from a first location to a secondlocation and/or change the effective size of one or more spots. In theprior art, it would be unthinkable to shift a spot because such anaction would strand terrestrial transceivers. The terrestrialtransceivers would be stranded because the shifting of one or more spotswould leave some terrestrial terminals unable to communicate with a newspot of a different color.

However, in an exemplary embodiment, the transceivers are configured toeasily switch colors. Thus, in an exemplary method, the geographiclocation of one or more spots is shifted and the color of theterrestrial transceivers may be adjusted as needed.

In an exemplary embodiment, the spots are shifted such that a high loadgeographic region is covered by two or more overlapping spots. Forexample, with reference to FIGS. 29B and 29C, a particular geographicarea 9210 may have a very high load of data traffic. In this exemplaryembodiment, area 9210 is only served by spot 1 at a first point in timeillustrated by FIG. 29B. At a second point in time illustrated by FIG.29C, the spots have been shifted such that area 9210 is now served orcovered by spots 1, 2, and 3. In this embodiment, terrestrialtransceivers in area 9210 may be adjusted such that some of thetransceivers are served by spot 1, others by spot 2, and yet others byspot 3. In other words, transceivers in area 9210 may be selectivelyassigned one of three colors. In this manner, the load in this area canbe shared or load-balanced.

In an exemplary embodiment, the switching of the satellites and/orterminals may occur with any regularity. For example, the polarizationmay be switched during the evening hours, and then switched back duringbusiness hours to reflect transmission load variations that occur overtime. In an exemplary embodiment, the polarization may be switchedthousands of times during the life of elements in the system.

In one exemplary embodiment, the color of the terminal is not determinedor assigned until installation of the terrestrial transceiver. This isin contrast to units shipped from the factory set as one particularcolor. The ability to ship a terrestrial transceiver without concern forits “color” facilitates simpler inventory processes, as only one unit(as opposed to two or four or more) need be stored. In an exemplaryembodiment, the terminal is installed, and then the color is set in anautomated manner (i.e., the technician can't make a human error) eithermanually or electronically. In another exemplary embodiment, the coloris set remotely such as being assigned by a remote central controlcenter. In another exemplary embodiment, the unit itself determines thebest color and operates at that color.

As can be noted, the determination of what color to use for a particularterminal may be based on any number of factors. The color may be basedon what signal is strongest, based on relative bandwidth availablebetween available colors, randomly assigned among available colors,based on geographic considerations, based on temporal considerations(such as weather, bandwidth usage, events, work patterns, days of theweek, sporting events, and/or the like), and or the like. Previously, aterrestrial consumer broadband terminal was not capable of determiningwhat color to use based on conditions at the moment of install orquickly, remotely varied during use.

In accordance with an exemplary embodiment, the system is configured tofacilitate remote addressability of subscriber terminals. In oneexemplary embodiment, the system is configured to remotely address aspecific terminal. The system may be configured to address eachsubscriber terminal. In another exemplary embodiment, a group ofsubscriber terminals may be addressable. This may occur using any numberof methods now known, or hereafter invented, to communicate instructionswith a specific transceiver and/or group of subscriber terminals. Thus,a remote signal may command a terminal or group of terminals to switchfrom one color to another color. The terminals may be addressable in anysuitable manner. In one exemplary embodiment, an IP address isassociated with each terminal. In an exemplary embodiment, the terminalsmay be addressable through the modems or set top boxes (e.g., via theinternet). Thus, in accordance with an exemplary embodiment, the systemis configured for remotely changing a characteristic polarization of asubscriber terminal by sending a command addressed to a particularterminal. This may facilitate load balancing and the like. The sub-groupcould be a geographic sub group within a larger geographic area, or anyother group formed on any suitable basis.

In this manner, an individual unit may be controlled on a one to onebasis. Similarly, all of the units in a sub-group may be commanded tochange colors at the same time. In one embodiment, a group is brokeninto small sub-groups (e.g., 100 sub groups each comprising 1% of theterminals in the larger grouping). Other sub-groups might comprise 5%,10%, 20%, 35%, 50% of the terminals, and the like. The granularity ofthe subgroups may facilitate more fine tuning in the load balancing.

Thus, an individual with a four color switchable transceiver that islocated at location A on the map (see FIG. 28, Practical DistributionIllustration), would have available to them colors U1, U2, and U3. Thetransceiver could be switched to operate on one of those three colors asbest suits the needs at the time. Likewise, location B on the map wouldhave colors U1 and U3 available. Lastly, location C on the map wouldhave color U1 available. In many practical circumstances, a transceiverwill have two or three color options available in a particular area.

It should be noted that colors U5 and U6 might also be used and furtherincrease the options of colors to use in a spot beam pattern. This mayalso further increase the options available to a particular transceiverin a particular location. Although described as a four or six colorembodiment, any suitable number of colors may be used for colorswitching as described herein. Also, although described herein as asatellite, it is intended that the description is valid for othersimilar remote communication systems that are configured to communicatewith the transceiver.

The frequency range/polarization of the terminal may be selected atleast one of remotely, locally, manually, or some combination thereof.In one exemplary embodiment, the terminal is configured to be remotelycontrolled to switch from one frequency range/polarization to another.For example, the terminal may receive a signal from a central systemthat controls switching the frequency range/polarization. The centralsystem may determine that load changes have significantly slowed downthe left hand polarized channel, but that the right hand polarizedchannel has available bandwidth. The central system could then remotelyswitch the polarization of a number of terminals. This would improvechannel availability for switched and non-switched users alike.Moreover, the units to switch may be selected based on geography,weather, use characteristics, individual bandwidth requirements, and/orother considerations. Furthermore, the switching of frequencyrange/polarization could be in response to the customer calling thecompany about poor transmission quality.

It should be noted that although described herein in the context ofswitching both frequency range and polarization, benefits and advantagessimilar to those discussed herein may be realized when switching justone of frequency or polarization.

The frequency range switching described herein may be performed in anynumber of ways. In an exemplary embodiment, the frequency rangeswitching is performed electronically. For example, the frequency rangeswitching may be implemented by adjusting phase shifters in a phasedarray, switching between fixed frequency oscillators or converters,and/or using a tunable dual conversion transmitter comprising a tunableoscillator signal. Additional aspects of frequency switching for usewith the present invention are disclosed in U.S. application Ser. No.12/614,293 entitled “DUAL CONVERSION TRANSMITTER WITH SINGLE LOCALOSCILLATOR” which was filed on Nov. 6, 2009; the contents of which arehereby incorporated by reference in their entirety.

In accordance with another exemplary embodiment, the polarizationswitching described herein may be performed in any number of ways. In anexemplary embodiment, the polarization switching is performedelectronically by adjusting the relative phase of signals at orthogonalantenna ports. In another exemplary embodiment, the polarizationswitching is performed mechanically. For example, the polarizationswitching may be implemented by use of a trumpet switch. The trumpetswitch may be actuated electronically. For example, the trumpet switchmay be actuated by electronic magnet, servo, an inductor, a solenoid, aspring, a motor, an electro-mechanical device, or any combinationthereof. Moreover, the switching mechanism can be any mechanismconfigured to move and maintain the position of trumpet switch.Furthermore, in an exemplary embodiment, trumpet switch is held inposition by a latching mechanism. The latching mechanism, for example,may be fixed magnets. The latching mechanism keeps trumpet switch inplace until the antenna is switched to another polarization.

As described herein, the terminal may be configured to receive a signalcausing switching and the signal may be from a remote source. Forexample, the remote source may be a central office. In another example,an installer or customer can switch the polarization using a localcomputer connected to the terminal which sends commands to the switch.In another embodiment, an installer or customer can switch thepolarization using the television set-top box which in turn sendssignals to the switch. The polarization switching may occur duringinstallation, as a means to increase performance, or as another optionfor troubleshooting poor performance.

In other exemplary embodiments, manual methods may be used to change aterminal from one polarization to another. This can be accomplished byphysically moving a switch within the housing of the system or byextending the switch outside the housing to make it easier to manuallyswitch the polarization. This could be done by either an installer orcustomer.

Some exemplary embodiments of the above mentioned multi-colorembodiments may benefits over the prior art. For instance, in anexemplary embodiment, a low cost consumer broadband terrestrial terminalantenna system may include an antenna, a transceiver in signalcommunication with the antenna, and a polarity switch configured tocause the antenna system to switch between a first polarity and a secondpolarity. In this exemplary embodiment, the antenna system may beconfigured to operate at the first polarity and/or the second polarity.

In an exemplary embodiment, a method of system resource load balancingis disclosed. In this exemplary embodiment, the method may include thesteps of: (1) determining that load on a first spotbeam is higher than adesired level and that load on a second spotbeam is low enough toaccommodate additional load; (2) identifying, as available forswitching, consumer broadband terrestrial terminals on the first spotbeam that are in view of the second spotbeam; (3) sending a remotecommand to the available for switching terminals; and (4) switchingcolor in said terminals from the first beam to the second beam based onthe remote command. In this exemplary embodiment, the first and secondspot beams are each a different color.

In an exemplary embodiment, a satellite communication system isdisclosed. In this exemplary embodiment, the satellite communicationsystem may include: a satellite configured to broadcast multiplespotbeams; a plurality of user terminal antenna systems in variousgeographic locations; and a remote system controller configured tocommand at least some of the subset of the plurality of user terminalantenna systems to switch at least one of a polarity and a frequency toswitch from the first spot beam to the second spotbeam. In thisexemplary embodiment, the multiple spot beams may include at least afirst spotbeam of a first color and a second spotbeam of a second color.In this exemplary embodiment, at least a subset of the plurality of userterminal antenna systems may be located within view of both the firstand second spotbeams.

The following applications are related to this subject matter: U.S.application Ser. No. 12/759,123, entitled “ACTIVE BUTLER AND BLASSMATRICES,” which was filed on Apr. 13, 2010, now U.S. Pat. No.8,289,209; U.S. application Ser. No. 12/759,043, entitled “ACTIVEHYBRIDS FOR ANTENNA SYSTEMS,” which was filed on Apr. 13, 2010, now U.S.Pat. No. 8,400,235; U.S. application Ser. No. 12/759,064, entitled“ACTIVE FEED FORWARD AMPLIFIER,” which was filed on Apr. 13, 2010, nowU.S. Pat. No. 8,030,998; U.S. application Ser. No. 12/759,130, entitled“ACTIVE PHASED ARRAY ARCHITECTURE,” was filed on Apr. 13, 2010, now U.S.Pat. No. 8,228,232; U.S. application Ser. No. 12/758,996, entitled“PRESELECTOR AMPLIFIER,” which was filed on Apr. 13, 2010, now U.S. Pat.No. 8,452,251; U.S. application Ser. No. 12/759,148, entitled “ACTIVEPOWER SPLITTER,” which was filed on Apr. 13, 2010, now U.S. Pat. No.8,289,083; U.S. application Ser. No. 12/759,112, entitled “HALF-DUPLEXPHASED ARRAY ANTENNA SYSTEM,” which was filed on Apr. 13, 2010 (docketno. 55424.00500); U.S. application Ser. No. 12/759,113, entitled“DIGITAL AMPLITUDE CONTROL OF ACTIVE VECTOR GENERATOR,” which was filedon Apr. 13, 2010, now U.S. Pat. No. 8,416,882; the contents of which arehereby incorporated by reference for any purpose in their entirety.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as critical, required, or essentialfeatures or elements of any or all the claims. As used herein, the terms“includes,” “including,” “comprises,” “comprising,” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises a list ofelements does not include only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, no element described herein is requiredfor the practice of the invention unless expressly described as“essential” or “critical.”

1. (canceled)
 2. A dual-circular polarization multi-beam receive antennacomprising: a first network of splitters to receive a verticalpolarization signal from a radiating element, and to divide the verticalpolarization signal into a plurality of divided vertical polarizationsignals; a second network of splitters to receive a horizontalpolarization signal from the radiating element, and to divide thehorizontal polarization signal into a plurality of divided horizontalpolarization signals; and a beam steering portion to form a plurality ofcircular polarized beams from the plurality of divided verticalpolarization signals and the plurality of divided horizontalpolarization signals, wherein the beam steering portion comprises vectorgenerators to adjust the divided vertical polarization signals and thedivided horizontal polarization signals prior to forming the circularpolarized beams.
 3. The receive antenna of claim 2, wherein the beamsteering portion comprises: a filter to inject a 90° relative phasedifference between a divided vertical polarization signal of the dividedvertical polarization signals and a divided horizontal polarizationsignal of the divided horizontal polarization signals, and to combinethe divided vertical polarization signal and the divided horizontalpolarization signal to generate a combined phase adjusted signal; and avector generator of the vector generators to adjust the divided verticalpolarization signal and the divided horizontal polarization signal byadjusting at least one of phase and amplitude of the combined phaseadjusted signal to form a circular polarized beam of the plurality ofcircular polarized beams, wherein the vector generator comprises a firstquadrant select in parallel with a second quadrant select and a firstvariable gain amplifier in parallel with a second variable gainamplifier.
 4. The receive antenna of claim 2, wherein a vector generatorof the vector generators comprises a modified vector generatorcomprising: a first quadrant select to generate a first quadrant shiftedsignal from a divided vertical polarization signal of the dividedvertical polarization signals; a second quadrant select to generate asecond quadrant shifted signal from a divided horizontal polarizationsignal of the horizontal polarization signals; a first variable gainamplifier to amplify the first quadrant shifted signal to form a firstamplified signal; a second variable gain amplifier to amplify the secondquadrant shifted signal to form a second amplified signal; and acombiner to combine the first amplified signal and the second amplifiedsignal to form a circular polarized beam of the plurality of circularpolarized beams.
 5. The receive antenna of claim 2, wherein the beamsteering portion comprises: a first vector generator of the vectorgenerators to adjust at least one of phase and amplitude of a dividedvertical polarization signal of the divided vertical polarizationsignals to form a first output signal; a second vector generator of thevector generators to adjust at least one of phase and amplitude of adivided horizontal polarization signal of the divided horizontalpolarization signals to form a second output signal; and a powercombiner to combine the first output signal and the second output signalto form a circular polarized beam of the plurality of circular polarizedbeams.
 6. The receive antenna of claim 2, wherein the plurality ofcircular polarized beams includes at least one right-hand circularpolarized beam and at least one left hand circular polarized beam. 7.The receive antenna of claim 2, wherein a vector generator of the vectorgenerators comprises: a first quadrant select in parallel with a secondquadrant select, and a first variable gain amplifier in parallel with asecond variable gain amplifier.
 8. The receive antenna of claim 3,wherein the filter is a quadrature allpass filter.
 9. A dual-circularpolarization multi-beam transmit antenna comprising: a beam steeringportion to form a plurality of pairs of vertical and horizontalpolarization signals from a plurality of input beams, wherein the beamsteering portion comprises vector generators to adjust the vertical andhorizontal polarization signals prior to forming the pairs; a firstnetwork of combiners to combine the vertical polarization signals of theplurality of pairs to form a combined vertical polarization signal, andto provide the combined vertical polarization signal to a radiatingelement; and a second network of combiners to combine the horizontalpolarization signals of the plurality of pairs to form a combinedhorizontal polarization signal, and to provide the combined horizontalpolarization signal to the radiating element.
 10. The transmit antennaof claim 9, wherein a vector generator of the vector generators adjustsa pair of a vertical polarization signal and a horizontal polarizationsignal by receiving an input beam of the plurality of input beams andadjusting at least one of phase and amplitude of the input beam togenerate an adjusted input beam, and the beam steering portion furthercomprises: a filter to divide the adjusted input beam to generate thepair of the vertical polarization signal and the horizontal polarizationsignal, wherein the filter is configured to inject a 90° relative phasedifference between the vertical polarization signal and the horizontalpolarization signal of the pair.
 11. The transmit antenna of claim 9,wherein the beam steering portion comprises: a power splitter to dividean input beam of the plurality of input beams to generate a firstdivided beam and a second divided beam; a first vector generator of thevector generators to adjust at least one of phase and amplitude of thefirst divided beam to generate a vertical polarization signal of a pairof the plurality of pairs; a second vector generator of the vectorgenerators to adjust at least one of phase and amplitude of the seconddivided beam to generate a horizontal polarization component of thepair; and wherein the first vector generator and the second vectorgenerator each comprise a first quadrant select in parallel with asecond quadrant select and a first variable gain amplifier in parallelwith a second variable gain amplifier.
 12. The transmit antenna of claim9, wherein the plurality of input beams includes at least one right-handcircular polarized beam and at least one left hand circular polarizedbeam.
 13. The transmit antenna of claim 9, wherein a vector generator ofthe vector generators comprises a first quadrant select in parallel witha second quadrant select and a first variable gain amplifier in parallelwith a second variable gain amplifier.
 14. The transmit antenna of claim10, wherein the filter is a quadrature allpass filter.
 15. A methodcomprising: receiving, by a first network of splitters of adual-circular polarization multi-beam receive antenna, a verticalpolarization signal from a radiating element and dividing the verticalpolarization signal into a plurality of divided vertical polarizationsignals; receiving, by a second network of splitters of the multi-beamreceive antenna, a horizontal polarization signal from the radiatingelement and dividing the horizontal polarization signal into a pluralityof divided horizontal polarization signals; adjusting, by vectorgenerators of a beam steering portion of the multi-beam receive antenna,the divided vertical polarization signals and the divided horizontalpolarization signals; and after the adjusting, forming, by the beamsteering portion, a plurality of circular polarized beams from thedivided vertical polarization signals and the divided horizontalpolarization signals.
 16. The method of claim 15, wherein the adjustingand the forming comprise: injecting, at a filter of the beam steeringportion, a 90° relative phase difference between a divided verticalpolarization signal of the divided vertical polarization signals and adivided horizontal polarization signal of the divided horizontalpolarization signals and combining the divided vertical polarizationsignal and the divided horizontal polarization signal to generate acombined phase adjusted signal; and adjusting, at a vector generator ofthe vector generators, at least one of phase and amplitude of thecombined phase adjusted signal, thereby forming a circular polarizedbeam of the plurality of circular polarized beams.
 17. The method ofclaim 15, further comprising receiving, at a modified vector generatorof the vector generators, a vertical polarization signal of theplurality of vertical polarization signals and a horizontal polarizationsignal of the plurality of horizontal polarization signals.
 18. Themethod of claim 15, wherein: the adjusting comprises: adjusting, at afirst vector generator of the vector generators, a divided verticalpolarization signal of the vertical polarization signals to form a firstoutput signal; and adjusting, at a second vector generator of the vectorgenerators, a divided horizontal polarization signal of the horizontalpolarization signals to form a second output signal; and the formingcomprises combining, at a power combiner of the beam steering portion,the first output signal from the first vector generator and the secondoutput signal from the second vector generator to form a circularpolarized beam of the plurality of circular polarized beams.
 19. Amethod comprising: forming, by a beam steering portion of adual-circular polarization multi-beam transmit antenna, a plurality ofpairs of vertical and horizontal polarization signals from a pluralityof input beams, wherein the forming includes adjusting, by vectorgenerators of the beam steering portion, the vertical and horizontalpolarization signals; transmitting, by the beam steering portion, thevertical polarization signals to a first network of combiners of themulti-beam transmit antenna, and transmitting the horizontalpolarization signals to a second network of combiners of the multi-beamtransmit antenna; combining, by the first network of combiners, thevertical polarization signals to form a combined vertical polarizationsignal, and providing the combined vertical polarization signal to aradiating element; and combining, by the second network of combiners,the horizontal polarization signals to form a combined horizontalpolarization signal, and providing the combined horizontal polarizationsignal to the radiating element.
 20. The method of claim 19, wherein theforming comprises: adjusting, at a vector generator of the vectorgenerators, at least one of phase and amplitude of an input beam of theinput beams to generate an adjusted input beam; and dividing, at afilter of the beam steering portion, the adjusted input beam togenerate, at the filter, a pair of a vertical polarization signal and ahorizontal polarization signal for the input beam, wherein the filter isconfigured to inject a 90° relative phase difference between thevertical polarization signal and the horizontal polarization signal. 21.The method of claim 19, wherein the forming comprises: dividing, at apower splitter of the beam steering portion, an input beam of the inputbeams into a first divided beam and a second divided beam; adjusting, ata first vector generator of the vector generators, at least one of phaseand amplitude of the first divided beam to generate a verticalpolarization signal of a pair for the input beam; adjusting, at a secondvector generator of the vector generators, at least one of phase andamplitude of the second divided beam to generate a horizontalpolarization signal of the pair for the input beam; and wherein thefirst vector generator and the second vector generator each comprise afirst quadrant select in parallel with a second quadrant select and afirst variable gain amplifier in parallel with a second variable gainamplifier.